Welcome to the Black Mesa Research Facility 

Hello, Mr. Freeman. Just sit back and enjoy the tram ride. You've got a long day 
ahead of you, and this is probably the only chance you'll get to relax. Look 
around the various locales, and pay attention to the voice on the loudspeaker. 
You never know what might come in handy later. I'm here to help you through your 
day. It's going to be rough. I'll assume you're planning a normally difficult 
workday, and also that you'll do some things on your own, such as search boxes 
in the workplace. There are plenty of supplies in Black Mesa, but sometimes you 
have to search for them.

Once you arrive at your destination, wait for the security guard to open the 
tram door. Follow him to the security door, and he'll let you in.

Anomalous Materials

You're running a little late, so let's try to get down to the test chamber as 
quickly as possible. Talk to the security guard at the front desk, then head 
down the hallway. Take the first right turn. At the first intersection, go 
right. The test chamber is to the left, but you need to put on the HEV suit 
before you'll be permitted access. Head down the hallway until you come to the 
locker room. Walk into the back, where the HEV suits are stored. Press the 
middle button on the console to open the storage pod, then walk down and put on 
the suit.

Before leaving the locker room, check your locker. It's on the back wall, near 
the stalls, and it's labeled with your name, "Freeman."
Inside, you'll find some energy for the HEV suit. Now leave the locker room and 
follow the hallway around to the test lab door. The security
guard will open the door. Press the button to open the elevator, then get in and 
press the button to activate the elevator. Once you're in the
lab, follow the hallway until you come to a group of Scientists who are waiting 
for you.

Talk to the Scientists. When they're done explaining today's experiment, they'll 
activate the retinal scanners. Walk to the second elevator and head down to the 
chamber. Two more Scientists will be waiting, and they'll briefly discuss the 
risks involved in today's
experiment. Seems there's a slight chance of a "resonance cascade scenario," 
whatever that is. But the administrator is adamant about
continuing, so once they activate the retinal scanners, go into the chamber. 

You'll be given specific instructions during the experiment. Climb up the ladder 
to the computer console, and then press the red button when prompted. Climb down 
the ladder and walk over to the metal cage on the floor. This is where the 
sample will appear when it's ready. When the sample appears, push the cart into 
the beam. 

So that's a resonance cascade scenario. Not good. 

Unforeseen Circumstances

You need to start making your way back up to the exit. Leave the test chamber, 
and use the retinal scanner. Normally, you'd be denied access, but it seems the 
accident has caused things to malfunction. Get in the elevator and go up. When 
you find the two Scientists, talk to the one who isn't injured. He'll follow you 
over to the security door and let you out. He'll also tell you to get to the 
surface. It's not going to be as easy as it sounds.

Before you go rushing into the next room, be careful. A high-powered energy beam 
is shooting out of the test chamber. Wait for it to
destroy the door, then time your run across the room so the beam doesn't hit 
you. You'll come to a room with a thin red laser beam.
Crawl under the beam, then walk carefully toward the end of the hallway. Wait 
for the second laser beam to make its way to the floor,
then run past. Pick up the Crowbar, break the glass on the door, and crawl 
through.

When you come to the second elevator, break the glass. There's no way you can 
prevent the tragedy that occurs, so crawl into the shaft and climb up the 
ladder. When you get to the next floor, you'll see a guard firing at two 
Zombies. Help him out with your Crowbar. If he
survives, ask him to follow you. If he's killed, take his pistol.

At this point, you can go back to the locker room. Guthrie's locker is open, and 
you can get some clips for the pistol. There's also a health dispenser back by 
the stalls. 

Now head to the main entrance area. A ventilation grate will be blown off by a 
nearby explosion, allowing you to crawl into the computer
room. You may want to head back out to the tram first, so hit the lock mechanism 
with the Crowbar. Obviously, the tram isn't going to help
you now. Head back in and climb through the vent into the computer room.

There's a health dispenser here, as well as a few Headcrabs. The Crowbar will 
work wonders on the crabs. Jump onto the fallen
computer in the middle of the room, then over to the computer on the far side of 
the room. Walk up the computer leaning on the wall to the
ventilation duct and climb out. Go through the hallway. Press the button to open 
the security door, beyond which you'll find a health
dispenser. If you don't have a pistol yet, you can find one on the dead guard 
lying under the health dispenser. 

You're about to have your first encounter with Houndeyes. These little beasts 
attack with a sonic discharge, and you can hear a high-pitched squeal as they 
rev up, which gives you a bit of time to kill them before they attack. Near the 
first pack of Houndeyes, there's a health dispenser through a window on the left 
as you enter. Jump through the window if you need to fill up. Follow the hallway 
around, killing any Houndeyes you come across. At the end of the passage, 
there's a metal door on the right. Go through and climb up the ladder. When you 
get to the top of the ladder, shoot the canisters to kill the Zombie and 
Headcrabs. Go down the right passage and talk to the Scientist so that he 
follows you. 

Follow the catwalk to a room with a Zombie finishing off another Scientist. Kill 
the beast. The Scientist following you will activate the
retinal scanner, giving you access to the supply room, filled with Grenades and 
ammo. After stocking up, leave the supply room and
go back down.

Continue following the passageway. You'll encounter your first Alien Slave, a 
cyclopean beast that shoots bolts of energy from its arms. If you see the energy 
surrounding its body, it is about to attack. It does quite a bit of electrical 
damage, so try to kill it before it gets the
chance to get you. Follow the hallway all the way to its end, where you'll find 
a Scientist hiding from some Headcrabs in a dumpster.
Behind the dumpster is a health dispenser. Nearby, there's a small hole in the 
ground next to a metal gate. A Zombie will crawl out of a
hole on the other side. Kill the beast by firing through the gate, then drop 
down into the hole. Follow the tubes until you come across a
valve. Turn the valve, and the tubes will begin filling with water. Swim through 
them until you come to a grate. It will open, and you can
climb out on the other side of the gate. 

You'll soon come upon a large freight elevator. The switch at the top of the 
ramp activates it. Flip the switch, then quickly get on the
elevator. As you descend, you'll be set upon by a constant stream of Headcrabs 
from above. Most won't be able to attack. Use the
Crowbar on those that don't go sliding off the elevator. Near the end of the 
elevator ride is a small platform with a health dispenser on it.
Be prepared to jump if you need to fill up. 

Next, you'll come to a metal catwalk. A Bullsquid will teleport in and break the 
bridge. Jump to the pipes and follow them around to the
ventilation duct. Break the grate with the Crowbar, then climb in. Follow the 
duct around to the second grate, and then break it and drop down. Beyond the 
crates, you'll come to another broken catwalk. On the far side, a Bullsquid is 
killing a bunch of Headcrabs. Let the squid deal with the crabs, then shoot the 
squid from afar. Now look up. Those are Barnacles. Shoot them from here, or just 
do your best to avoid their tendrils, which will pull you up into their waiting 
mouths. 

Jump into the water and go all the way to the end. You'll find a ladder leading 
up to a health dispenser. Follow the walkway around, and go through the door. 
You'll come to a room filled with suspended boxes. Climb up the ladders, then 
jump on the railing. Make your way across, jumping carefully from box to box. 
Once safely on the other side, follow the hallway until you come to a ladder. 
Climb up. You'll come across a large elevator. Enter and press the button. 

Office Complex

The first task facing you once you make it to the office complex is simply 
getting down the hallway. About halfway down the hall there's a live wire, 
randomly discharging electricity into the puddle on the floor. And the door that 
you can reach is locked. Luckily, there's a ventilation duct just before the 
live wire. Crawl over to the duct and break the grate with the Crowbar. Be 
careful, because the discharge can still hit you if you move too far to the 
right of the grate. Crawl into the duct and follow it to the end. Break the 
grate and climb into the room. Beware of the Barnacle, and be aware that more 
will be bursting through the ceiling while you're in the room.

In the corner, you'll see a door with a sign reading "high voltage." Open it, go 
in, and flip the switch. Now the hallway is safe.

At the other end of the hallway, you'll need to break the window and climb 
through. The water-filled room to the right has its own electrical problem, but 
you'll deal with that in a moment. For now, it's time to get some supplies. Go 
to the left and into the little alcove with the wooden door. A Zombie will begin 
bursting through the door. Wait until it has cleared a passage, and then kill 
it. Go in and get the pistol
clips. Go out and continue to the left until you come to some crates. Break them 
up, and continue on. 

You'll see a supply room with a locked gate. A security guard will be standing 
there, with a Zombie sneaking up behind. Kill the monster, and the guard will 
open the door to the supply room, wherein you get the Assault Shotgun. You can 
also find some health and HEV power if you climb down the ladder in the area 
just before the supply room. 

Now go back to the room filled with water. Jump up into the window, and then 
onto the table. You need to jump first to the sink, then to the table on the far 
wall (which is next to a health dispenser), and finally to the counter on the 
other side. Flip the switch to turn off the light. Turn on the flashlight, and 
drop down into the water. The closet near the sink has some HEV power in it. Now 
open the grate on the wall with the Crowbar and climb in. You'll have to deal 
with some Headcrabs, and make sure you duck under the fan. When you get to the 
end, break the grate, but don't jump in the room just yet.

The room below has a security turret inside, as that unlucky Scientist just 
discovered. You have two choices. You can disable it and get some health, or let 
it stay on and do some dirty work for you. To disable the turret, you must flip 
the switch under the ledge it is stationed above. Then just jump up the various 
boxes scattered about to get to the health. Alternately, you can drop into the 
room and run for the exit directly opposite. There, you'll see a herd of 
Headcrabs. Lure them into the other room, making a beeline for the door in the 
back. You'll make it to safety, but the turret will take down the Headcrabs.

The back room has some supplies, as well as a Bullsquid and some Alien Slaves 
that teleport in. Once you've dealt with and picked up everything, go back to 
the area where you encountered the Headcrabs. Go up the stairs. At the top, 
you'll encounter a guard. Get him to
follow you, then continue on into the offices. A number of Alien Slaves are 
waiting inside, so it'll be handy to have the guard around. There are also a 
number of supplies in the various offices, so hunt around if you're in need of 
ammo or health. 

Before you venture out of the offices, though, look for the lounge. You'll see a 
sign that says "maintenance access" over a couch.
Jump on the couch and break the ceiling panels with the Crowbar. Climb up the 
ladder. There's a security turret in the room, as well as
a switch to deactivate it. Step slightly into its view to activate it, then 
switch it off while it's readying itself (flipping the switch prematurely
will make it impossible to deactivate the turret). Grab the Assault Shotgun 
shells and head down the ladder.

Exit the offices, but beware of the Alien Slaves waiting near the stairs. There 
is also one hiding behind the vending machine just before the exit. Get rid of 
them, then go up the stairs, and deal with the Headcrabs at the top (these 
stairs are a much more pleasant experience if you've deactivated the turret). 
Follow the hallway to a sunken room with a boarded-up doorway at the far end. 
Approach the doorway, but be aware that the Zombie and Headcrabs will be coming 
up behind you. Use the Crowbar to open the doorway and continue on. 

At the end of the passage, you'll come to a lounge with some coffee machines and 
two Zombies. Put them out of their misery. There's
also a health dispenser on the wall. There's a doorway with some ice under it. 
This leads to the meat locker. Flip the metal switch next to
the door to open it, then enter the locker.

Upon entering the meat locker, turn left. In the far room, a Scientist will be 
running from a Bullsquid. Kill the squid, then pick up the Grenades in the room. 
In the back of the meat locker, you'll see some crates in a shadowy corner. As 
you approach, another Bullsquid will burst out of the crates. Deal with it, and 
then look on the wall for a red switch. Use the switch to activate the freight 
dolly.

Return to the entrance of the meat locker and climb the ladder to the top 
storage shelf. Crawl over to the ventilation duct, break the grate, and climb 
in. There are some Headcrabs around, so be ready to deal with them. Follow the 
duct to the end and break the grate. Follow the shelves around until you see a 
duct on the wall across the hallway. Wait for the freight dolly to pass by, then 
get on it. There are some HEV power canisters in the crates on the dolly, so you 
may want to get them before climbing into the duct. There is also one to the 
right just as you enter the duct, next to a dead guard. 

Follow the duct to a room filled with Barnacles. Kill them all, and don't miss 
the HEV power canister and Assault Shotgun shells on the
floor. Jump up the ducts until you get to the top of the room. Enter the open 
duct, follow it until it ends, then climb the stairs.

In the next hallway, a frightened Scientist will jump through a nearby window, a 
Zombie will break through a walkway above, and another will break through the 
wall. Kill both the beasts, then climb through the window into the supply room 
where you'll find some Assault
Shotgun shells, the Assault Shotgun (if you haven't picked it up yet), and some 
first aid kits. The alcove found through the hole in the wall
also holds a few items. 

Now you must climb up the elevator shaft at the far end of the hall. You'll need 
to make the jump to the ladder on the opposite wall. It's
quite a distance, so try to jump at the last possible moment (and you may want 
to save before your attempt - it's a long way down). Climb
up the ladder to the ledge, and then continue up two more ladders to the top. 
Unfortunately, there's no way to save the dangling Scientist.
At the top, you'll need to jump to the ladder on the elevator. Climb to the top, 
break the grate, and drop in. Open the doors and prepare to
meet the rescue team. 

"We've Got Hostiles"

Take this opportunity to fill up on health and HEV power at the two dispensing 
stations. The Scientist will be frantically pounding on the glass to the control 
room, begging the guard to open the silo door. Then he'll run off down the hall, 
walking through the blue laser. Lesson learned: Blue laser equals bad.

Follow the Scientist down the hall (you won't be able to access the security 
station until much later). At the end of the hall, you'll see two
red lasers. You're going to have a hard time avoiding them, so the best thing is 
to just run through and crouch behind the crate ahead.
The laser activates the turret, and you need to take it down. A well-placed 
Grenade will accomplish this nicely, as will a few Assault
Shotgun blasts (though you'll more than likely take considerable damage using 
the latter method). Search all the crates, deal with the
Headcrabs teleporting in, and move out of the room.  

Around the corner, there is a blue laser. If you can destroy the emitter, it 
will take out the laser. Unfortunately, you can't see the
emitter. A Grenade tossed in the vicinity will get rid of it, but make sure you 
stand back. There is another blue laser in the hall. Deal with
it in the same manner and move on.

You'll come to a kitchen area. Alien slaves will begin teleporting in. You 
should have just acquired the MP5, a handy weapon that fires
Grenades in its secondary fire mode (unfortunately, the Grenades themselves are 
few and far between). Take out the slaves, and don't
miss the health dispenser on the wall. Head down the ramp. There's a red laser 
here, just before a room filled with crates and
turret-mounted machine guns. You can jump over the laser, but get as far into 
the room as possible. As soon as you enter, some slaves
will teleport in, activating the turrets. Luckily, the turrets can handle them 
just fine. But, unfortunately, they've been activated. Lob a few
Grenades at them, or just take them out with your guns if you don't mind taking 
some damage. Now jump up to the top of the crate
stack, but don't drop down just yet. 

There are two more turrets on the other side of the crates. You can easily take 
out the one directly below you before it has time to
activate. The second, nestled by the fire door, is a little trickier. A Grenade 
will do the trick, but be careful not to throw it too close to the
fire door, or else the door will close. If it does begin closing, jump down and 
crawl under, or simply wait a few moments, and you can
open it with the red button on the wall. As soon as you jump down from the 
crates, Headcrabs will begin teleporting in. Take care of
them and keep moving.

At this point, you will have begun hearing announcements that Black Mesa is now 
under military command. All you need to do is make it to the surface and you're 
home free. You're close, so hang in there.  

You'll come to another stack of crates. Climb over, but be careful when you 
climb down. The floor is wet and there's a gaping elevator
shaft at the far end. There's also a red laser just around the corner, with two 
turrets waiting in the hall beyond. Grenades are your friends
here. Bounce one or two into the hallway to take out the turrets, then carefully 
walk across the water into the hall.

Climb up the ladders in the next room. You'll see a Scientist talking with a 
soldier. Yikes. So much for the cavalry. Kill the soldier, and
keep moving. Take the elevator, and you'll come to another room with some 
soldiers. These are tricky enemies, but you should be able to
handle a few of them while they're concentrating on killing the Scientists. Make 
sure you don't try to hide from the soldiers (they
aren't too shabby at aiming Grenades), just keep moving and firing.

Cross the catwalk. This is a good time to shoot those Barnacles on the ceiling 
above. They're no threat now, but they'll be trouble later. At the next 
intersection, there are some blue lasers to the left. Go right into a room with 
a conveyor belt and a few Barnacles on the ceiling.
Shoot the Barnacles if you don't want to try to avoid them, and climb on the 
conveyor. Run along its length until you come to another
room. There are health and HEV power dispensers, as well as some ammo for the 
MP5. Jump up the boxes and onto the conveyor. Run
along it and around the corner.

Before entering the next room, shoot the canisters next to the conveyor. There's 
some hostile activity ahead, and you don't want to
be next to the canisters when the bullets start flying. Take out the soldier 
behind the barricade. There's a health dispenser on the wall
across the bridge as well as some ammo. There are three turrets on the floor 
under the bridge. Get rid of them, then jump down. You can
ignore the blue lasers in the hall - you've already been that way. Go in the 
direction away from the lasers. 

You've got a pretty nasty fight with some soldiers next. They have the height 
advantage, and they'll stay hidden. Try to keep moving, avoiding the Barnacles 
if you can. If you're lucky, a soldier or two will get caught in the Barnacles' 
tendrils. Once the soldiers are gone, climb up the stairs. At the top, there's a 
health dispenser and some ammo, but watch out for the Barnacle hiding in the 
shadows on the top level.

Keep moving across the bridge, until you come to a large open room. There are 
several soldiers waiting down there for you, and one will undoubtedly lob a 
Grenade at you almost immediately. The best tactic is to run in, MP5 blazing, 
and pick them off as they run for
cover.

You'll soon come across the elevator to the surface. Be careful, as you've seen 
how unwelcome you are in the eyes of the welcoming
committee. Head up, and use the health dispenser near the door if you need it. 
Three soldiers are waiting for you outside. Be aware that
once you take them out, more will come. Run out of the facility and to the left. 
You'll see a small door with a ladder. Climb down.

In the hallway at the bottom of the ladder, you'll see a door leading to the 
control ventilation shaft. Open it and step back. As soon as the debris is 
cleared, get down to the ladder on the wall and climb down to the duct opening. 
Soldiers will be following you, so watch your
back. In the next shaft, there are three duct openings. The top two lead around 
to various places you've seen but couldn't reach before,
most containing supplies. The bottom duct leads to where you need to be. Follow 
it, then head to the middle duct in the next shaft. Be
careful of the fan. 

This duct will lead to control room you saw when you first entered the area. A 
Scientist will tell you to try to make it to silo D. Looks like the surface 
isn't your answer. First the aliens are after you, now the military. And things 
are about to get worse. Press the red button on
the panel, then leave the control room and enter silo D. 

Blast Pit

Things are about to get more dangerous. Use the Crowbar to knock away the 
blockade. In the next room, you'll see a control booth. Throw the switch to 
summon the elevator, then climb down and get on. At the bottom, climb into the 
freight cart.

Activate the cart with the "use" key. You can control the speed by using the 
"move forward" and "move back" keys while the cart control
is active. There will be many Houndeyes and a few Bullsquids in the tunnel. Kill 
them or just set the cart to top speed and avoid them. As
you reach the end of the tracks, make sure the cart is at full power. You'll be 
thrown across the radioactive waste onto the crates floating
within. The crate you land on will break apart, but you can get on the others 
without taking too much damage. Make it to the cement
platform on the other side by jumping across boxes. Kill the Bullsquid there, 
then climb up the ladder onto the pipe.

On the side of the chamber, there is a pipe with an opening in it. Drop down 
into the opening and follow the pipe. At the end, jump out. Jump up to the pipe 
running along the top of the room. Walk over to the balcony and jump onto it 
(you can also make it from the lower pipe,
but it's a bit more difficult). You'll come to another chamber full of 
radioactive waste. Jump onto the pipe and climb up to the elevator.
There are some first aid kits and HEV suit power canisters on the far wall to 
your left as you enter the chamber. To get there, jump onto
the silo base and follow it over to the ledge. 

Activate the elevator and take it up. At the top, you'll encounter some 
Houndeyes, a Bullsquid, and some Headcrabs. Be cautious when shooting enemies on 
the bridge. If you hit the canisters, they'll explode and you'll have to make a 
difficult jump across the gap. Enter
the silo. 

Inside, you'll see that things are worse than you imagined. A huge beast has 
taken up residence in the silo. You'll have to get ride of it,
but conventional weapons aren't going to work. After the Tentacle attacks the 
Scientist, leave the control room. Climb the ladder leading
to the silo entrance, but first take out the Barnacle hanging above.

Destroying the Tentacle takes some effort. There are a few steps, but there are 
some things you can do to make it easier.

First off, the Tentacle only responds to sound and motion. Crawling puts you in 
stealth mode, which should help you sneak past its deadly beak. Grenades are 
once again your friends here. Throw a Grenade at the crates blocking the ladder 
on the level below you. The Tentacle will go attack that level. Throw another at 
the boarded-up door on the second floor of the pit; the Grenade will (if your 
aim is good) take out the boards. Finally, throw the third to the bottom, 
clearing a path to the door. Climb down the ladder, and stay crouched while you 
move.  Make your way to the doorway on the second level.

Once through the doorway, you're temporarily safe. Exit the silo. If you 
accidentally blow up the bridge while shooting at the Zombie, just jump onto the 
pipes to make it across. Follow the pipes to the fuel room. Unfortunately, the 
door is locked. You need to find another way
in. Near the door is a ladder down. At the bottom are two Zombies. Kill them and 
head down. Go to the grate and break it with the
Crowbar. Climb down the ladder to the pipes below. Walk along the pipes and go 
left at the intersection. You'll come to a ladder. Climb
up. 

Shoot the Zombie and break the grate at the top of the ladder. Grab the Grenades 
in the adjacent room, then go down the hall and
activate the door. Two more Zombies await you. Take them out, then climb down 
the ladders to the fan. Get to the fan switch. Before
switching it, prepare to move quickly. Once you activate the fan, get back to 
the ladder as fast as you can and climb up. Now look up.
That's where you want to be. Once the fan gets going at top speed, jump in the 
air stream. 

At the top, break into the vent with the Crowbar. Climb in and prepare to fight 
a few Headcrabs. Make your way through the crawl space,
removing any blockades with the Crowbar. You'll come to a ladder down. Climb 
down and take out the Zombies in the fuel room. Push
the buttons marked "fuel" and "oxygen." This will start the flow of both to the 
blast pit. Climb up the ladder in the room to the exit and head
back across the bridge to the blast pit. 

You need to get to the doorway on the bottom level of the blast pit. If you can 
manage it, throw a Grenade down to clear out the doorway, then throw another up 
onto a higher level to distract the Tentacle. Crawl down to the first level.

If you need to use the Crowbar to clear the doorway, do it fast. The sound will 
attract the Tentacle and that beak is sharp. Go through the
doorway, then jump over the huge gap in the catwalk. The next door will lead to 
another bridge, again blocked by some explosive
canisters. If you hit them while fighting the Bullsquid across the way, use the 
small pipe to make your way to the other side. 

Follow the hallway around, across the puddle and into the large open chamber. 
There's a Bullsquid and some Barnacles in the room. Kill them, then walk out to 
the elevator controls and summon the elevator. Climb in. It will stop halfway 
down. Jump to the ladder on the
wall and climb down. At the bottom, talk to the Scientist. He'll tell you to 
reactivate the reactor.

Walk down the hallway, then jump on the pipe to avoid the radioactive spill. 
Kill the Zombie, then walk out onto the platform and push the button. The 
platform will move to the opposite side of the chamber. Climb up the ladder. 
Watch the platform that is moving quickly back and forth. Time your jump down 
from the ladder so that you are following the platform. Quickly make it to 
either of the ladders and climb up. Push the button on the reactor, and quickly 
climb about halfway back down the ladder. Wait for the platform to pass again, 
then run to the other ladder. Hug the walls to make sure the platform doesn't 
knock you off. Climb up the second ladder, and push the second button. This will 
start the reactor. Climb back down, all the way to the bottom. Use the platform 
to get back to the chamber entrance. 

Once again, avoid the radioactive spill by walking on the pipes. There's a 
health dispenser near the Scientist, so use it if you must.
The elevator is out of commission, so get back to the ladder. Climb up near the 
top of the ladder. To the right there's a very small ledge,
which you can jump to. Walk around the ledge and drop down to the walkway. 
There's a health dispenser in the room.

You need to get across the puddle in the adjacent hallway, which will be a 
problem now that the power is back on. Push a few of the boxes into the room to 
create a makeshift bridge. You'll probably still need to jump a fair way to make 
it across.

Head back to the blast pit, then start making your way up. Always crawl, and use 
Grenades to focus the Tentacle's attention on other
levels if needed. Once at the top, go to the control room and hit the test fire 
button. This will get rid of the Tentacle and clear the opening
at the bottom of the pit, allowing you through. Climb down the ladder. Don't 
relax now that the Tentacle is gone; you have a bigger fish to
fry next. 

At the bottom of the ladder is a pit, and it's quite a fall. Try to land in the 
water. Swim up and search the ledge. You'll find the .357, a great
handgun with a lot of stopping power. Get back in the water and swim under the 
pipes until you emerge in an area filled with radioactive waste. Climb down the 
ladder to the health and HEV power dispensers, then climb back up. 

Jump onto the pipe running the length of the room, then follow it until you 
can't fit through the passage. Drop to the pipe below on the right. Follow it to 
the huge pipe, and climb to the top. Turn the valve to extend the pipe. Drop 
down into the opening and follow the pipe,
jumping over the gap. Eventually, the pipe will break away under you and you'll 
fall into a room filled with crates. Search the crates to find
some trip laser mines, then head into the hallway.

Power Up

You'll come to a large chamber with a Gargantua fighting some soldiers. Don't 
stop to watch, because the beast will come for you next. Head quickly into the 
passage just ahead and to the right. You need to make it to the power generator. 
Unfortunately, the passage is
blocked, and the place is teeming with Alien Slaves. Fight your way to the 
entrance to the track control room. The walkway will collapse
beneath you. This is OK; you don't need to enter the control room yet. Turn 
around, and follow the hallway around. 

Fight your way through the Headcrabs and Alien Slaves, following the signs to 
the power generator. You'll pass a health dispenser near the blocked stairway. 
Keep moving down the hallway until you come to a valve. Turn the valve to open 
the door to the hazard waste chamber. 

Climb up the ladders to the top room. There are some soldiers and a turret 
waiting for you. Search the crates in the room, then head down the hallway. 
You'll come to a heavily fortified area. A soldier waits behind a barricade, but 
there are some explosive crates behind him. Shoot the crates. If you're in need 
of health, there's a small alcove just below the entrance ramp with a health 
dispenser and some
Grenades. Head up the ramp behind the barricade. To the right, there's a number 
of soldiers. To the left there are a few soldiers, as
well as a number of crates filled with supplies. Clear out the area to the left 
first, then head back down the hallway to the right. 

A herd of Headcrabs will be dropping in from the ceiling. Let the soldiers and 
the Headcrabs fight each other, then dispose of anyone
that's left. There's an HEV power dispenser just inside the room. Press the 
button to activate the elevator, but don't get on. Look down.
Blue lasers are waiting for you. Toss down a Grenade to take them out, then wait 
for the elevator, press the button again, and get on. 

When the elevator reaches the bottom, you'll have to fight a few Houndeyes. 
Follow the walkway around to the staircase. Take the stairs all the way down to 
the maintenance level, near the flooded generator. Watch out for the Zombie. 
Break the box blocking the generator mechanism, then head up to the next floor. 
Enter the generator control room, then push the button on the left to turn the 
generator on. Turn around. A sporadic electric beam is blocking the doorway. 
Time your exit carefully to avoid it. There's a health dispenser just near the 
staircase. Use it if necessary, then head back to the elevator. 

Another group of guards has occupied the area. Take the elevator up and prepare 
to fight your way back to the track control room.

You still don't need to enter the control room. Instead, climb up the ladder and 
jump the gap in the broken hallway. Head back into the
room with the beast, and make a quick left down the previously gated area. He 
should follow. If not, take a few shots at him to get his
attention. At the end of the passage, you'll come to a large generator. Run up 
the stairs to the control switch and turn it on. The beast will
walk right into the electrical beam. 

Now leave through the door at the bottom of the steps, and head back out into 
the main area. Climb on the freight car and drive it onto
the track direction controller. Get off and run back to the track control room. 
Use the HEV power dispenser, then flip the switch to change
the track direction. Leave the control room (you can just jump through the 
window if you'd like), climb on the cart, and drive into the
tunnel.

On a Rail

Drive the cart until you come to the blockade. Talk to the security guard. He'll 
tell you that you need to launch the satellite to put an end to the invasion. 
The military has shut it down, and you have to remedy the situation. Get off the 
cart, grab the first aid kits, and flip the switch to raise the blockade. Before 
getting back on the cart, run into the other room and shoot the Barnacles on the 
ceiling. Then drive the cart onto the lift.

The lift will go down. Move forward through the flooded tunnel. Don't fall off - 
that water is electrified. At the top, watch for the HEV power
canister on the right. Stop the cart, get off, and pick it up. Get back on the 
cart and continue forward. You'll pass an intersection with a crane
blocking the track to the left. Kill the Houndeyes and move on. Leave the track 
switchers alone for now. Follow the track along until you come to a small alcove 
with a Bullsquid and a dead soldier. Stop the cart, kill the squid, and jump 
onto the platform. Get the first aid kit. The crates at the end of the room 
contain an HEV power canister and a Grenade. Get back on the cart. As you move 
forward, watch out for the Barnacles on the ceiling above. 

At the next alcove, kill the squid. Stop the cart and get off. There's a 
stairway here, with a health dispenser at the bottom. Climb the stairs. Use a 
Grenade to take out the crates. If the Grenade didn't take out the turret 
beyond, dispose of it quickly. Flip the switch in the control room to move the 
crane. Climb back down to the cart and continue forward. When you see the track 
switcher, shoot it so that you see the arrow pointing left. The cart will move 
to the track previously blocked by the crane.

You'll come to a lift. Some soldiers are waiting above. The best tactic is to 
wait until the lift begins to ascend, then jump off. Climb up the ladder and 
take out the grunt on the first level. There's a health dispenser and some ammo 
here. Climb the ladder to the second level. Carefully take out the grunt waiting 
on the tracks ahead, then jump onto the cart and move forward.

Around the first bend, there will be a serious firefight with some soldiers. 
Deal with the one on the right, then use the barricades for
cover. If you want, you can use the mounted gun to take out the rest. On the 
wall is a switch. Flip it to raise the blockade on the track.
Before moving on, do a little exploring.  

Up the stairs near the barricade, numerous soldiers are fighting some Alien 
Slaves. Clear out the stragglers (and beware of the soldier
hiding behind the wall in the office at the top of the stairs). Follow the 
hallway around until you reach another staircase. A soldier waits at the
bottom. The hallway goes left and right. To the left, you'll come to a part of 
the track blocked by two blue lasers. Shoot the emitters to remove the threat. 
Move back and head the other way down the hall, where you'll find some soldiers 
fighting some slaves. Finish off whoever is left.  

Before going back up, look under the stairway. Turn on your flashlight and break 
the crate to find a power canister. Break the grate and
drop down to find some first aid kits and ammo guarded by some Headcrabs. Now go 
back up and get back to the cart. Jump across
the track and to the other side, where the soldiers have killed some Alien 
Slaves. There's a switch here you must flip to lift another
blockade. Head up the stairs. Fight your way to the back room, where you'll find 
an HEV power dispenser.

Go back down, board the cart, and move forward.

At the end of the track, you'll encounter some soldiers. You may want to stop 
the cart just before the end and take them out with a Grenade. Search the 
bodies, then jump across the tracks to the hallway. Fight the slaves and the 
soldiers and keep moving. You'll come to a boarded door; behind it is a security 
guard and some crates. In the room across the hall, you'll find a health 
dispenser hidden behind some crates. But watch out for the Headcrabs falling 
from the ceiling.

At the end of the hall, a huge barricade protects a soldier firing a mounted 
gun. Use the crates as shields and make your way across
the tracks, out of the gun's range. Back where the graffiti says "Surrender 
Freeman," you can toss a Grenade into the barricade to
kill the soldier. Go through the blast door and crawl under the blue lasers. 
Kill the soldier on the walkway below, then climb down the
ladder. Go through the blast door. And search the crates in the office for some 
Magnum rounds. There's also an HEV power dispenser
hidden behind the office. 

Get on the freight cart and move forward.

Duck under the red lasers to avoid having to deal with the turrets beyond. Near 
the third turret, you'll see a door. Jump off and go in to
find some ammo, along with a Bullsquid, a Barnacle, and some Headcrabs. Get back 
on the cart and keep moving. Around the next
bend, a rocket launcher will begin firing at you. Strafe back and forth on the 
cart to avoid its fire. Take out the soldier just beyond the rocket
launcher. 

Blue lasers block the tunnel, so set the cart to a slower speed and jump off. 
Follow behind it on the ledge next to the track. It will activate
the lasers and you won't get hurt. Jump back on the cart when the path is clear.

Jump off at the next area, which is teeming with Alien Slaves. Kill them all, 
and use the health dispenser. Go through the hallway until
you come to a stairway blocked by some crates. Jump over the crates and head up. 
Kill the soldiers and flip the switch to raise the
blockade. There's an HEV power dispenser here. Go down to the track. Don't get 
back on the cart you rode in on - that track leads to a
deadly trap. Jump on the other and move forward.

Stop well before you get to the next blockade. There's a large group of soldiers 
nearby, guarding the switch. Try to take them out
without entering the room yet; there's a large gun waiting around the corner. 
Run in and climb the ladder, making your way next to the gun.
Throw a Grenade into the barricade to take out the gunner. Use the dispenser, 
flip the switch, and get back on the cart.

Stop the cart before you get to the lift. There are numerous soldiers, and it's 
easier to fight them on foot. Climb up and search the crates. Walk around the 
small ledge of the lift shaft to find the items nestled in the open grate. Once 
the area is clear, climb down to the cart and move it onto the lift. 

At the top, some stray electric surges sporadically block the path. Stop the 
cart before each one and time your movement forward so
you don't get hurt. Set the cart on its slowest speed, jump off, and follow. 
It'll activate the laser traps waiting around the next corner. Get
back on and duck under the boxes in the next room. At the blockade, two soldiers 
will be waiting. Take them down and flip the switch.

Stay down through the next room and the next tunnel, avoiding both the crates 
moving overhead and the rocket volleys being fired your
way. Take out the soldier as you pass the rocket launcher. The next room has 
more stray electricity. Time your movements so you don't
get hurt. At the track switcher, shoot it so the arrow is facing forward. You're 
about to hit the end of the line.

Get off the cart and toss a Grenade down the ladder chute to take out the blue 
laser below. Climb down, and jump off the ladder to avoid activating the 
turrets. In the room at the bottom, you'll find some Grenades, a health 
dispenser, and some Zombies. Move down the
track when you're finished here. Around the bend, you'll find a big gun. Use the 
crates and barricades to avoid its fire. Take out the
soldier and then kill the gunner with a Grenade. Search the crates and head up 
the stairs. 

Outside, listen to the soldiers talk about you, then kill them. Watch out for 
the hidden turret on the wall to the left. Head toward the blast
door, and open it with the keypad. You'll have to fight three more soldiers to 
make it to the next blast door. There's a big gun in the
corner to your left that will help, along with some first aid and Assault 
Shotgun shells. Once the soldiers are gone, go in. Those red lasers
blocking the stairway are lethal. Use the metal crates to make a ladder up to 
the ledge, then jump up, avoiding the stairs altogether.

Through the door you'll see two more soldiers. In the computer room, you'll find 
a health dispenser. Get to the control room and push the big red launch button. 
After the rocket has launched, head out of the control room and back outside. Go 
through the big blast doors
and head through the huge door, which is now open.

Climb down the ladder; you'll find plenty of supplies in the crates, including 
some Satchel Charges. Get on the cart and start moving
forward.  

Apprehension

When you see the soldier throw the explosive on the track, jump off of the cart. 
Kill the soldiers and jump into the flooded chamber below. Explore the various 
rooms on the first level to find some ammo. The room is divided into two parts: 
the side with the cart you were just thrown from and the other side. If you get 
stuck on the cart side of the barricade, you can wait until the barrels are 
released to jump across. Fight the tormented Scientists, and then make your way 
up to the health dispenser. Once you land back in the flooded room, jump to the 
other side of the barricade. The door at the bottom of the pool is the one you 
want. Keep the Crowbar ready to fight the alien larvae
that'll bite you along the way. Follow the underwater passage, and go through 
the first metal door on your right to get some air. 

Keep swimming down the hall. You'll come to a room with a grate on the floor. 
Break it, swim down, and take the passage to the right to
find a room with lots of ammo. Open the door and leave the room .Go through the 
passage straight ahead, where you'll find dry land. 

In the next room, you'll find some Barnacles and a pool containing an 
Ichthyosaur. Follow the walkway around to the ladder. Climb up and talk to the 
Scientist, who will tell you about the tranquilizer Crossbow in the next room. 
There are health and power dispensers on the wall if you need them. Walk out 
onto the beam and drop into the shark cage to get the Crossbow. The cage will 
fall into the pool. Shoot the
Ichthyosaur with the Crossbow until it stops moving. Swim up to get some air. Go 
underwater again and find the valve near the pipes.
Turn it to open the grate. Swim under the grate, get the tranquilizer ammo, and 
walk up the stairs. 

Follow the stairs up and go left at the top. In the next room, you'll see some 
Barnacles and some shells on a crate. When you jump on the crate, some slaves 
will teleport in. Kill them and enter the hallway. 

Around the corner, you'll see a wet walkway with some Ichthyosaurs swimming in a 
pool below. Carefully walk along it, jumping over the
first gap and staying in the middle. After the first turn, the walkway will 
partially collapse and a slave will teleport in. If you're in the middle, you'll 
be OK. If you fall in, hurry to the ladder behind you and climb back up. Walk to 
the second gap in the walkway and jump over. It's a difficult leap to make. Once 
at the end, jump into the hole in the fence and swim into the passage under the 
sign that says "generator control."

When you emerge, kill the Bullsquids. Go through the passage on the right and 
push the crate off the walkway. Turn on the generator by pushing the button on 
the control panel. Drop down to the floor. Walk to the middle piston. Jump onto 
the bottom pedestal, but be sure not to be under the piston. Jump on the piston 
when it lowers, then jump off, onto the ledge to get the charges. Drop down. 
Push the metal crate
to the wooden crate blocking the ladder in the corner. Jump onto the metal crate 
and break the wooden crate with the Crowbar. Jump up
and climb the ladder. 

In the next hallway, you'll find a health dispenser. Be careful. As you approach 
it, a Bullsquid will teleport in. Kill it and go down the hall.

In the computer room up the stairs, you'll encounter some slaves and some 
Headcrabs. Clear out the room and the Scientist will open the security door. Use 
the HEV power dispenser on the wall and talk to the Scientist. Open the door to 
the freezer and quickly fight your way
to the ladder in the back. Climb down.  

Follow the colored pipes to the elevator, killing the slaves that teleport in on 
the way. Take the elevator up and talk to the guard. He'll get assassinated 
halfway through his sentence. Hunt down the Human Assassins waiting in the next 
area, keeping your back to the wall so they don't sneak up on you. The sniping 
mode on the Crossbow is a good way to get rid of them. In the area, there's a 
small U-shaped tunnel that leads to a supply room. You can wait for the Human 
Assassins there, as they will come after you. In the supply room you'll find 
ammo and a health dispenser. Once the Human Assassins are gone, climb up the 
stairs to the access switch. Turn the switch to open the doors, then run 
through. Free at last.

Um, not quite. You need to quickly jump up the boxes to escape the trash 
compactor. Once you're safely on the ledge, walk across the
compactor and pick up the Crowbar on the opposite ledge. Now climb down the 
ladder and go through the grate on the floor. 

Residue Processing

Follow the pipe until you come out in an outdoor area. Run to the opening and 
continue on to the silo, fighting the Headcrabs that appear. Turn the valve, 
quickly climb up the ladder, and drop onto the lift going down. Turn on the 
flashlight and enter the pipe. Follow the pipe to the grate. Break it and drop 
down. The guard can't be saved. The Barnacles will get him. Wait until his 
remains drop and grab the gun, then take out the Barnacles. Use the health 
dispenser on the far wall. Walk down the hallway to the observation area. Avoid 
the Barnacles. Walk down the stairs to the HEV power dispenser, and use the 
Crowbar to get rid of the Headcrabs. Both doors are locked, so walk back up.  

Walk back to where you first entered the plant. Climb up the ladder on the vat 
and jump across the floating debris. Plan to do a lot of jumping in this area.

When you exit the pipe, you'll need to jump across the rising platforms to the 
exit on the other side. Jump to the platform to your right as
it rises, then jump straight ahead as the next platform goes downs. Quickly jump 
to the platform in the corner of the room, then over to
the platform near the exit. Jump to the exit and continue on. If you fall, you 
need to climb up the ladder on the platform near where you
entered. 

In the next room climb along the pipe on the left side of the room. When it gets 
narrow, jump to the pipe on the right. Exit the room. In the
following room, there are two rotating arms in a vat of hazardous waste. Before 
you make your way across, you may want to use the health
dispenser on the wall in the room, below the vat. There's a ladder down just to 
the left of where you entered. To get across the vat, jump to the first turning 
arm. Walk out to the end and jump to the second arm as it passes. Stand on the 
end of the second arm to reach the exit pipe. 

In the next room, jump off of the conveyor belt and search the crates to get 
some ammo and first aid kits. Get back on the belt and ride it
up. You'll drop down into some liquid waste. Follow the stream into the second 
room, but quickly make your way to either side and climb
out before the grinder crushes you. Follow the passageway and jump back into the 
liquid. Swim down and around the second grinder. Stay
submerged to avoid the flames in the next room. Swim under the third grinder, 
and then go into the small alcove to your right, where
you'll find a health dispenser.  

Drop back down into the water and climb out on the right side of the next room. 
You'll pick up a .357, which you can use to kill the Bullsquid attacking the 
security guard. In the control room, you'll find a health dispenser, some 
Satchel Charges, and some HEV power canisters. There is another control room 
with three levers just to the right of the conveyor belts. These control the 
direction of the belts. Make sure all three belts are moving away from the 
water, and then go back to the control room with the dead guard. 

The button on the control panel will stop the stampers for a short period of 
time. Try to stop them when both the right and middle stampers are up. Run over 
and jump on the right belt. Jump to the middle belt and ride it out of the room. 
You'll have to avoid some horizontally moving pistons in the next passage. Time 
your movements so you don't get hurt. The next passage has vertically moving 
pistons. Their patterns are erratic, so hang back until you know it is safe to 
move. 

In the next area, you need to make your way from conveyor belt to conveyor belt. 
If you fall, follow the signs to the exit. You'll pass a
health dispenser and a Bullsquid on the way, and start back near the beginning 
of the belt maze. Keep jumping from belt to belt. Move
quickly in the furnace as you pass through. When you come to two belts running 
in opposite directions, drop to the one moving away
from you, on the left as you look down. Throw a Satchel Charge on the other and 
detonate just after it passes by the blue laser. This will
not only take out that laser, but also another one around the corner, out of 
view. 

Follow the passage around and jump from belt to belt in the next area to avoid 
the rollers. Drop to the floor below, and drop through the jaws as they open. As 
you approach the end of the conveyor, jump to the ledge, but watch out for the 
Barnacles. Walk through the hallway.

Questionable Ethics

Climb up the ladder and break the grate with the Crowbar. There are numerous 
Houndeyes in the next room. Before climbing up, throw a Satchel Charge in the 
room and climb down. Detonate the charge. If you don't have any, you'll have to 
take your chances with firepower. Climb up and jump onto the box by the 
electrified fence, then to the kennel on the right. Jump over the fence. Use the 
health dispenser, then head down the hallway. 

Look at the grunt in the glass cage. He'll begin pounding on the glass. Quickly 
break the glass on the red button and press it. The grunt will escape, but you 
can run down the hall and avoid serious damage. Get to the small lab at the end 
of the hall and enter the control room.
If the grunt is following, wait until he enters the room and press the button. 
Use the health dispenser on the wall and exit the lab. Kill the
soldier outside the door and talk to the guard. Walk up the ramp.

Take out the soldiers in the entry area. At this point, you should have acquired 
an Assault Shotgun and an MP5. Head up the stairs and
around to the second small lab. Open the cages by pressing the button between 
them, then run into the control room. You may want to have the guard wait 
outside if he's following you. Press the button in the control room to clear out 
the Headcrabs, then search the cages for the Crossbow and some Snarks.

Exit the lab and walk down. Drop some Snarks into the hallway, then take out the 
remaining soldiers. Turn right at the intersection and head down the sloped 
walkway. Walk through the room at the bottom, grab the HEV power canisters, and 
go through the doorway up to the
observation booth. Pick up the laser emitters on the way. Shoot the active laser 
emitters in the corner of the room below, and grunts, both alien and human, will 
come into the room. Watch the battle, then head back down to kill the survivors 
and search the bodies. 

Walk into the newly opened passage, and follow it around (killing the soldiers 
in your path) until you come to a stack of boxes. Break through the first few 
boxes, but be careful not to activate the laser trap in the back of the room. 
Use the health dispenser and keep
moving down the hallway, past the Headcrabs in the glass cages. When the cages 
break open, kill the crabs and move to the middle of
the hall and up the steps. 

Some soldiers will be fighting Bullsquids. Wait until they're finished, then 
move in. Kill the survivors. In the first passage on the left, listen
to the Scientist and his assistant discuss the experiment. When everything goes 
kaboom, go in and pick up the Gauss Gun. Push the
red button on the console to activate the laser. Go back to the main hallway and 
enter the room just ahead. Push the button to activate
the second laser. Pick up the HEV power canisters, then walk all the way to the 
room at the end of the hall. Push the red button on the
console near the health dispenser to activate the third laser. Finally, walk 
down the hallway across from here to the room filled with
Houndeyes. Activate the fourth laser. 

Search the crates in the area for ammo, then go into the room where all of the 
lasers are headed. Push the crate against the wall under
the laser shield, then activate the beam. It will blow a hole in the wall. Jump 
to the pipe, then down to the ledge, and finally to the ground.
Open the door and talk to the Scientists. In the next room, turn off the 
surgical unit. Ask one of the Scientists to follow you and walk down the hallway 
past the Headcrab cages. If you haven't killed them yet, you'll have to so that 
the Scientist will follow you. 

Walk back to the entry area, and the Scientist will open the security door. 
Listen to the Scientist, who'll tell you he's going to alert the
lambda team that you're on the way. Go through the revolving door. Kill the 
soldier just outside the door. Shoot the explosive boxes
blocking the tunnel, then run to avoid the turret fire. Press the button to open 
the door, and get ready to fight your way to the lambda
complex. 

Surface Tension

Beyond the door, several soldiers will be waiting. They're surrounded by a 
number of explosive canisters, so some well-placed shots will make your work 
much easier. Once the area is clear, search the bodies and pick up the first aid 
kits scattered about. Continue on into the rock opening. Don't be hasty running 
into the next area. An Apache is circling overhead. Wait until it makes a pass, 
then run toward the
dam and jump in the water to the right. Watch out for the Ichthyosaur swimming 
around. If it gets too close, take it out with the Crossbow.

Swim over to the ladder and climb up. In the control room at the top, push the 
button labeled "turbine control." Jump back into the water.
Swim down to the valve at the base of the dam. Turn it to open the grate and 
swim in. You'll emerge on the other side. There's an HEV power canister on a 
rock to the left, but be careful to avoid the Apache's fire as you grab it. Stay 
submerged while the Apache is overhead, and keep swimming toward the ladder on 
the far end. When the sky is clear, climb up and enter one of the two pipe 
openings. 

Run through the pipe and over to the ladder on the wall. Climb up. Follow the 
ledge around to the second ladder and climb up to the clearing. You'll see a 
sign that says "high voltage" next to a fence. Immediately to the left is a 
small passage through the rocks. Go through. You'll see a sign reading "storm 
drain hatch." Follow the area to a small alcove in the rocks. Numerous soldiers 
will chase you, so take them out from the safety of the alcove. After the 
soldiers are gone, wait for the Apache to pass, then run out. There's a small 
cement building nearby. Enter it and turn the valve. Follow the wall to the 
right back to the passage through the rocks. 

Continue following the wall until you come to another opening. Go through. 
You'll see a Tentacle coming out of the sand, surrounded by
items. Beware of the burrowed Headcrabs. Throw a Grenade to get the Tentacle out 
of the way, then run over and pick up the stuff. Run
behind the large rock on the hill and through the small passage behind it. You 
emerge in a minefield. Follow the wall to the left until
you come to a tent. Shoot the ground in front of the tent to detonate any mines, 
then continue following the wall. When you come to the
storm drain, jump over the fence and climb down.

Be careful when emerging from the drain. It's a long way down. Edge your way 
out, taking out the turret to your right. Use the sniper mode on the Crossbow to 
take out the soldier on the level below the turret. Then slowly move toward the 
right of the ledge you're on. There's a soldier directly below you. Kill him, 
then drop to the small ledge. Follow the ledge around the pipe, and take out the 
soldier waiting in the alcove. 

Now you need to slide down the pipe and land on the outcropping below. You may 
want to kill the soldiers waiting down there first.
Follow the metal walkway to the right, and jump across the wooden bridge to get 
the HEV power canister (don't walk across the bridge - it
isn't very sturdy).

Walk back to the pipe and continue along the rock ledge. You'll come to some 
large metal doors with a single soldier guarding them. Kill him, then go through 
the doors. Inside, you'll find the RPG. An old friend will show up again, but 
now you can deal with him. Run out into
the cave and wait for the Apache to appear. Aim the RPG at the helicopter, then 
fire at will. Remember, you must keep the laser sight
on your target to score a hit. Two or so rockets should take down the 
helicopter. Once it's gone, search the crates and continue along the
ledge. 

Climb up the ladder to the next ledge. You'll need to walk up a rock ramp and 
jump on some small ledges. It's quite tricky, but it helps if
you're walking (not running) along the edge so you can make more precise 
movements. Climb up the second ladder and walk along the ledge to the storm 
drain. Be prepared for the Headcrab that will jump out. Climb into the drain. 

Follow the drain until you come to an intersection. This next part is tricky no 
matter what you do, but here's a good tactic. Follow the
drain passage to the left. When you get to the ladder at the end, climb up so 
that you're just peaking over the top of the drain. Use the
sniper mode on the Crossbow to take out the soldiers, one by one. 

Climb out of the drain and into the soldiers' camp. Watch the tank; it will be 
trying to hit you. It's slow, giving you time to run up close and
around the back. Another soldier will be waiting for you in the storage bay. 
Kill him, then search the crates and use the health dispenser. Run over and 
activate the door in front of the tank, then hurry through before it gets a 
chance to fire. 

There's another tank waiting in the next area. Use the crates to block its fire 
and make your way down behind it. Jump through the hole in the wall to find a 
supply tent guarded by two soldiers. You'll find ammo, health, and HEV power in 
the crates. Climb up the hill, back through the hole, and run down through the 
door at the bottom of the path.

An alien transport will drop a grunt and a slave in your path. Kill them both. 
Walk around to the right side of the building and jump onto the fallen girder 
and over the blue laser. Walk around the path, avoiding the falling debris. Walk 
down the steps and jump over the two blue
lasers in the alley. As you emerge, be careful of the large turret on the wall 
to the right. Use an explosive to take it out (the Grenade
launcher works fine). Walk past the dying guard. There's a small minefield 
ahead, so use the Glock to clear a path. Around the corner,
there's another turret on the wall. Get rid of it with an explosive. Climb under 
the barbed wire and make your way to the other side of the
yard, avoiding the electricity. 

When you're safely on the far side of the yard, shoot the canisters next to the 
power supply. This will make it safe to climb up the fallen
tower to the roof. Walk along the roof until you find an opening. Drop down to 
the boxes below and talk to the Scientist. Leave the room.
Search the room across the hall for some laser bombs. In the hallway, use the 
boxes to jump over the lasers. Push the first box just up to the first laser and 
jump up and over. Push the second to the base of the stairs and do the same. Do 
not set any of the lasers off - it will cause a fatal chain reaction. 

Open the metal door to the left. Jump up the boxes and into the room below. 
Crawl through the gap in the box stack. Find the crate labeled "fragile," 
blocking two beams. Break a passage through it. Shoot the Headcrabs on the other 
side quickly; they have a nasty habit of jumping through the beams. Walk over to 
the elevator and destroy the large crate. Now walk up the stairs near the red 
light, crawling
under the laser blocking your way.  

At the top, kill the Headcrab and jump over the beam. Activate the elevator and 
get on. You need to jump from here to the elevator
below. Good luck. When you make it safely, activate the elevator and head down. 

Pick up the Hornet Gun at the bottom of the elevator. Search the crates, where 
you'll find a wide variety of ammo. A guard will come
screaming down the corridor, followed by some soldiers. Be careful where you 
shoot - there are explosives everywhere. It may be a good time to try out that 
new gun - just aim in your target's general direction and shoot. No ammo needed.

Follow the corridor around until you see a truck next to a ramp. Don't run up 
yet - and alien transport will drop some grunts. Not to worry, though, a 
subsequent bombing run will take them out. Wait until they're gone and run up. 
Immediately head up the ramp to your right. Search the crates, and be prepared 
to run for it. Run along the wall toward the armored vehicle, zigzagging to 
avoid its fire. Kill the soldiers on the way. Quickly run into the alley behind 
the building. There's a turret on the wall at the entrance to the alley. Get rid 
of it with an explosive. Enter the building and kill the two waiting soldiers.

Head up the stairs and talk to the security guard. Get him to open the supply 
closet. Take everything, then walk over to the window. Jump to the ledge and 
follow it around the building to the right. Get on the power cabinet, and then 
jump to the cabinet across the way. Jump to the fire escape and climb up to the 
roof. Look down into the courtyard. You'll need to make it to the door on the 
opposite side.
First, deal with the soldiers on the ground. Then walk down the small ledge next 
to the wooden plank leading down. Jump to the platform
on the right, then jump across to the doorway. 

You'll emerge in a large landing area. Quickly run and hide in the small room to 
your right. Watch the soldiers and the grunts fight, then kill the survivors. 
Run into the hangar and down the walkway. Kill the grunt in the hallway and open 
the doors back into the alley. Go find the guard in the building (the one who 
opened the supply room for you), and get him to follow you to the security door 
near the hangar. 

More soldiers will be dropped in, so be careful. When the guard opens the door, 
run in. There's health and HEV power dispensers
inside. Search the crates, then get up to the big gun. Fire the gun at any 
remaining soldiers, then at the huge doors in the landing area.
Take out the grunts that emerge and get to the doors. 

Round the corner and use the big gun to take out the slaves as they teleport in. 
When the coast is clear, run up and step on the big,
organic trampoline in the middle of the courtyard. It will throw you up to the 
level above. Soldiers and aliens are fighting below. Wait until
one side loses, then drop down and kill the survivors. Search the crates, and 
then break the grate on the duct and climb in. Be
prepared to kill a few Snarks as you climb up. Continue up the duct. When you 
reach the next grate, break it, but back up. Some guards
will begin shooting at the duct. Wait until they're done, then toss some Snarks 
down into the garage. Once the soldiers are gone, drop
down yourself.

Open the door on the far side of the garage. Back up when you see the Grenades 
coming - there's no exiting that way. When the wall is blown open, use the 
controls to lower the car elevator. Use the controls again, then jump on the 
elevator as it starts to rise (don't forget to use the health dispenser, as 
you'll probably need it at this point). Jump through the hole and kill the 
soldiers. 

Grab the big gun and blow open the door. Use it to take out the Alien Grunts who 
come streaming out as well. Around the next corner, more soldiers are fighting 
aliens. Let them do most of the work. Kill the stragglers, then climb down and 
search the bodies. Go through the
remains of the door in the corner to find a supply room filled with ammo and HEV 
power canisters. Climb up and jump the gap in the catwalk. Kill the Alien Slave 
waiting beyond. Head into the hallway. There's a health dispenser to your left. 
Go down the hallway. An Alien Grunt will throw a soldier through the wall. Kill 
him and move on. 

Around the corner you'll come upon more fighting. Drop down the crates and clear 
out the area. Walk to the organic trampoline, which
will throw you to the roof across the way. Break the grate on the roof and drop 
down into the water. Climb into the pipe and start heading
forward. When the soldier throws in the bomb, move back quickly into the water. 
When it explodes, go to the end of the pipe and exit.
Fight the soldier, and then move into the next room, where a soldier is fighting 
some Headcrabs. If you need some health, drop to the
floor and use the dispenser - otherwise, jump to the pipe at the end of the 
catwalk and turn the valve. Enter the pipe, climb the ladder, and
follow the pipe around. Drop down to the staircase and kill the soldier. Go up 
the stairs and get the guard to follow you. 

Down the stairs is a room with a security door, a soldier, and a health 
dispenser. The guard will open the door. Back outside, you'll see a grunt on the 
roof and a slave. Kill the slave and use the sniper mode on the Crossbow to kill 
the grunt. Make sure the guard is still
following you. Run right to the control booth, and the guard will open the door. 

Inside the parking garage, a Gargantua is killing soldiers. Run up the ramp to 
avoid the same fate. Use the trampoline to get up to the wall, then run to the 
second tower with the air strike map. Use the controls to mark the area of the 
wall with the gate on it. Use the left control to adjust the horizontal plane on 
the map and the right to adjust the vertical. When the monster begins breaking 
through the gate, call in the air strike by pushing the middle button. You'll 
need to mark three more targets on the map as well. First, mark the huge steel 
doors in the corner and call in the strike. Next, clear out an area of the wall 
to the right of the doors. Finally, call in a strike aimed at the tower just in 
front of you, which will create a bridge to the doors. Once you've made a path, 
run across the tower and through the doors.

"Forget about Freeman!"

You'll come to a room with a collapsing ceiling. Look up and keep moving to 
ensure nothing hits you. Climb up and over the debris, then go through the 
doorway. 

In the next room you'll hear the military announce it is moving out. Good 
riddance. Climb over the railing and down into the room. A little
ways in, some grunts and slaves are waiting. No need to waste ammo. Run back to 
the room where you heard the announcement
(use the girders to jump over the railing) and turn on the turret. There are a 
few grunts, and some more slaves will teleport in, but the turret
will take care of most of them. You can manage whatever's left. Make sure you 
turn off the turret before leaving the control room, though.
Jump over the railing and climb up the crates in the middle of the room. Jump 
over to the elevator platform to use the health dispenser.
Now jump back over the railing and down to the floor.

The hallway just outside the room goes left and right. Right will lead you out 
of this area. Go left first. Use the Crowbar to break through
the mesh walls that block your way, and destroy the alien pods. These will 
release Snarks that you'll have to run from or shoot. At the
end of the passage is a large room filled with crates and Alien Grunts. As you 
enter, more grunts will teleport in at the entrance. Kill
everything, then search the wooden crates. The trampoline will give you access 
to the ledge above (with Snarks and first aid kits) and the
top of the metal crate stack (with some ammo). Now go back down the hallway.

Around the bend, you'll come upon some Alien Slaves. Kill them, then run up to 
the platform, and destroy the pod blocking the hatch. Turn the valve to open the 
hatch and climb down the ladder. At the bottom, crawl under the red laser. Kill 
the Headcrab and disable the turret. Jump across the water to the platform in 
the middle. Search the wooden crates for some health, and then push the metal 
crate into
the water (either side). Jump onto the crate and jump over the gate.

Follow the water around and turn left. Kill the Headcrab and jump into the 
water. Apart from an Ichthyosaur, the big, open pool in front of you holds 
nothing of interest, so swim to the passage immediately to the left and climb 
over the small embankment. Get close to the cog and duck. Crawl between a gap in 
the gears. Swim under the two pipes ahead, then between the two that follow. Get 
some air before
continuing. At the next cog, duck again and time it so you move with a gap in 
the gears. When you emerge, you'll be face-to-face with a
turret and a soldier. Get rid of them, pick up the ammo, and climb the ladder.

On the surface, you'll face two soldiers and a tank. Get out of the tank's 
range, using the rocks as barricades. Kill the soldiers and
move behind the tank. Watch out for the turret hidden in the corner just to the 
left as you approach the elevator. Use the health
dispenser, then push the button to call the elevator. At the top, go down the 
hall and turn right. Two soldiers are guarding the stairs in
the next room. To the right of the stairs you'll find a crate with a first aid 
kit inside. Climb the stairs and peek out into the large warehouse
beyond. Once again, some soldiers are fighting some grunts. Wait until they're 
done and clear out the room. Drop down to the tank. Use
the big gun to blow up the door just ahead, then grab the mounted gun to kill 
the slaves and grunts that will begin pouring in. Walk down
to the end of the hall, but don't go through just yet.

Grunts guard either end of the next hall, but your biggest concern is the laser 
turret to the left. As you enter the hall, step back because
the large section of wall just in front of you will collapse. Hit the turret 
with the Gauss Gun, and then take out the grunts to the left. There is also
one to the right, so dispose of him if you feel the need. Follow the hallway 
left and open the door. Press the yellow button inside to access lambda core.

Lambda Core

Enter the control room and push the button. Get on the freight elevator next to 
the truck and ride it down. In the room below, several Headcrabs and a Bullsquid 
await. Search the crates and climb up the ladder to the health dispenser. Go 
through the small metal door to the ladder. 

You'll enter hazardous materials bay A. There are several Human Assassins on the 
ground floor and two on the walkway above.
There's a passage to the right blocked by crates. Break through and climb the 
stairs to the catwalk. Walk over to the passage on the left.
Go down the stairs to access health and HEV power dispensers. Go up the stairs 
and follow the hallway to the elevator. Ride the elevator
down.

Open the door to hazardous materials bay B. Two Alien Grunts will be waiting. 
Move back to the hallway and take them out. Another will
teleport in. Use the explosive canisters just next to it for an easier kill. One 
more will teleport into the storage bay. Once it's gone, climb up
the ladder to the door and talk to the Scientist. He'll tell you about the 
Lambda reactor, then open the security door. Enter the reactor.

Use the dispensers on the left, then ride the lift up to the second level. Turn 
right and enter the test firing lab. Pick up the EGON and
the ammo from the shelf. You can open the firing chambers and kill the Headcrabs 
and Bullsquid beyond, but it isn't necessary. Exit the
lab and go down the hall to the coolant system elevator.

Turn right and follow the signs to the maintenance station. Talk to the guard 
and the Scientist. Get the ammo and use the dispensers. Now leave the station 
and return up the stairs. Follow the blue paint on the walls to coolant system 
01. Fight your way to pump station 01, and flip the switch on the pump. Go back 
to the main area and follow the orange paint to coolant system 02. You'll need 
to jump over some debris and fight a number of guards on your way to the next 
pump station. The catwalk just before the pump station will collapse as an Alien 
Grunt teleports in. Jump the gap, avoid the Barnacles, and keep moving. Just 
before the pump station, turn the valve to shut off the steam
pipe. 

Fight the Headcrabs in the pump room, then flip the switch. Get the HEV power 
canisters and make your way back to the main area.

Follow the sign reading "auxiliary tank reactor access." In the tank room, a 
number of grunts will be teleporting in. You can either fight or just drop into 
the tank and avoid them. Follow the water to the reactor core. Turn both valves 
to flood the reactor. Climb the ladders, avoiding the energy beams and jumping 
the gaps, to reactor core D.

Follow the hallway around, and then enter the supply cabinet for ammo and HEV 
power. Enter the elevator and climb the ladder to level B. Jump from the ladder 
to the broken door. Check the supply cabinet to the right, then go down the 
hall. Open to door to the
security station on the right. Talk to the guard and use the health dispenser. 
Enter the hallway and fight the grunts and slaves that
await you. At the far end of the hall are more grunts. Lure them into the 
hallway under the pipes, and then throw the steam valve. They'll
fry quickly. 

Go down the hallway and turn the corner. At the end, you'll see a ladder. Climb 
down to level C. Jump onto the crates and over the
fence. Jump off the left side of the pipe to get some supplies, then jump back 
again over the girder at the other side. Climb the ladder
and head back up to level B. 

Enter the level B reactor core. What follows is a series of teleporters you must 
enter in the correct sequence. You enter the orange
glowing portals and exit the green portals. As you enter the ports in the core, 
make sure you time your teleporting so that you land on the
rotating platforms. Stand on the ledge of each port and look up to see when the 
platforms are in place. Following is the correct sequence
for the teleporters:

Jump into the teleporter at the base of the core. Jump into port 2. Duck under 
the pipe and jump into port 4. Jump into port 7. The various other ports will 
lead to some supply areas, so you may want to do a little exploring.

Once you've jumped through port 7, you'll emerge in another teleportation room. 
Jump across the waste to the rotating platform in the center. You need to make 
it into the areas labeled "01" and "02." In each is a switch that will open half 
of the doorway to the teleporter. This is very difficult, so you may want to 
save your game each step of the way. The best method is to drop from the outer 
platforms to the middle platform when it is down, then drop to the inner 
platform. Going the other way, jump quickly from the inner platforms to the 
outer platforms and into the necessary areas, skipping the middle ring 
altogether. When the door is open, jump into the teleporter.

You'll reach a new area on level B. Kill the Headcrabs and search the debris for 
HEV power. Then climb the ladder to level A. The Scientist will open the glass 
doors. Talk to him about what you need to do, gather the supplies, especially 
the jump module. Once you've taken the module, the Scientist will let you into 
the portal control room. Inside, use the dispensers and climb the ladder to the 
platform. Kill
the flying beasts that enter while the portal is being opened. Once the 
technician gives you the go ahead, long jump (duck-jump) into the
beam. 

Xen

Upon entering Xen, you must long jump from platform to platform until you reach 
the large structure and below. Drop down onto one of the
passing platforms or any of the beams jutting out, and then jump onto the ledge 
around the structure. Be careful. There are numerous
Houndeyes about, and those purple lights shoot energy. The pools you see will 
restore your health if you stand in them.

You'll find a small passage in the rock. Crawl through and break the mesh on the 
small crawl space. Climb through the hole. In the chamber, you'll see three 
metal, toadstool-shaped pedestals. Activate them with the "use" key. Break the 
mesh cage with the luminous leaves in it. These will flutter to the pedestals 
and activate the teleporter in the center of the room.

Gonarch's Lair

When you enter Gonarch's lair, wait for the beast to come galloping out of her 
cave. Use some heavy weaponry on her, aiming for the sac dangling beneath her 
armored shell. When the small insects attack you, use the Glock or the Crowbar 
to get rid of them. They're a nuisance, but they'll do a lot of damage, a little 
at a time. When you've done some damage to Gonarch, she will go running off into 
the cave. Don't follow yet. Pick up the ammo and HEV power lying around the dead 
Scientist. There's also a health pool on a platform floating off to the side if 
you need it. Now follow Gonarch.

In the second chamber, keep attacking. Avoid the covered pit in the center of 
the area. There are some items down below, but it's a long fall if you miss the 
ledge. Continue fighting Gonarch until she breaks through the mesh into the next 
area. Kill the accumulating insects and follow Gonarch.

Drop down to the thin ledge with the glowing crystal on it. Then drop down into 
the tunnel. Chase Gonarch down the tunnel. As you fall into the next chamber, 
try to land on the mesh before falling to the ground to avoid taking damage. 
Grab the HEV power and ammo, then
continue shooting Gonarch. She will fall through the mesh onto the ground. Shoot 
her until she dies. Fall down the hole her death rattle
creates into the teleporter.

Interloper

This part is extremely tricky. There are several elements to this region: the 
blowholes on the ground, the rotating platforms, the pillars, and the mantas 
flying through the air. You need to get to the cave on the far side of the area. 
Enter the cave and fall into the small pit. Hit the
webbing to fall into the room below. Follow the passage (you'll encounter a 
number of enemies as well as some items), destroying any webbing in your path 
with the crowbar. You'll come to a dead end with some webbing in the corner. 
Break it, and a pillar will lower from 
above. Get on the pillar and ride it up, then jump down the platforms. When you 
get near the bottom, jump onto one of the blue mantas'
backs. Ride it to the teleporter.

In the next area, run out of the cave. Run left to the healing pool. Now climb 
over the ridge and run past the machinery to the cave opening. There are many 
grunts around, so fight when necessary. In the cave, go through the partially 
blocked passage. There's a huge creature in the next room. Load up the RPG and 
give it a few taps, or lob some Grenades. When the monster is gone, jump over 
the rocks into the cave. Crawl into the small passage to pick up the Snarks and 
first aid kit, then head out the opening toward the Tentacle. 

Watch for the Barnacle on the ridge, and then crawl along, avoiding the 
Tentacle's beak. Use Grenades to make it attack the lower level if necessary 
(there's also a first aid kit down there you may want to risk grabbing). Attack 
the grunts by the teleporter and get in.

Enter the factory. Follow the ramp around, killing the slaves and flying 
creatures guarding the area. Get on the elevator and take it up to the second 
level. Go to the healing pod to the right on the second level. Jump on the 
elevator gear and get up to the conveyors. Run across the connector to the 
second connector, then ride it into the water. Run along the platform, and jump 
over the conveyor. Follow this
passage around. Kill the flying creatures and slaves (there's a healing pod just 
below if you need it). 

Follow the walkway around, killing anything in your path. Jump on the pistons 
and ride them up to the next level. Jump over the railing and enter the room 
full of huge canisters. Be wary of using explosives in this area - each of the 
containers has a grunt inside. Kill everything in the room, then get the 
supplies from the alcoves. Go through the passage on the left. You must break 
the containers to get through the
passage. In the next room, you'll find more enemies and a healing pod. Clear out 
the room, then climb into the red shafts on the ground.
Drop down the shaft to the next area of the factory.

Make your way across the walkway to the ramp. Go up and into the room with the 
healing pod. There are a few slaves along the way. Get healed, then go out and 
clean out the flying creatures. Get on the rotating elevator platform to the 
next level. Keep moving. If you're in need of supplies, check the two ducts on 
this level. They lead to a large room filled with an assortment of goods and 
some slaves. Follow the spiral ramp around, grabbing everything, and then head 
out when the area is empty. 

In the main area, get on the second rotating elevator platform. There's a health 
pod in the passage on the next level. Make your way
to the third rotating platform and go up to the teleporter. Jump in. 

In the next region, jump from platform to platform to the ominous red teleporter 
at the end. Get in, and prepare for your final battle.

Nihilanth

Nihilanth is a tough creature to beat. He sends out deadly electrical charges, 
as well as mobile teleporters. You'd be wise to avoid these. A shot from the 
Hornet Gun will get rid of them, as will hiding behind the various spires in the 
room. If Nihilanth does trap you with a teleporter, there are three areas you'll 
be sent to.

The first area is a large spiral tower. You must make your way to the teleporter 
at the top. There are some supplies here, so get them
while you can.

The second area is a small cave filled with flying creatures and rocks that 
float up to a teleporter at the top of a vertical shaft. There are some supplies 
in the blue alcove. Jump on any one of the rocks as it rests on the ground, then 
ride it up to the teleporter.

The third area is a platform around a pool of water. An Ichthyosaur dwells in 
the pool, but you need to land in it if you want to survive the
fall. Kill the grunts and use the organic trampolines to bounce up to the 
teleporter. Subsequent teleportations will bring you back to this area, with a 
Gargantua you must fight. 

To kill Nihilanth, you must destroy his power source. If you have enough 
rockets, shoot the orange glowing crystals on the wall. Two shots should do the 
trick. There are three crystals, and you can use any of your heavy weapons to 
destroy them. Once the three crystals are gone, start firing at Nihilanth. When 
his energy disappears, use the trampolines to bounce up above him. His head will 
open. Fire into
his vulnerable brain (a rocket would be most useful here). When he's destroyed, 
you've won the game.

Now you'll be given a choice by the administrator. Each leads to a different 
ending. Good luck on future assignments, Mr. Freeman. It's
been a pleasure working with you.