Just to set things straight, Darksheer is over-reacting with his additions to

Spycraft is a complex game with many different paths according to players
actions. For example it's possible to get recruited to Procat by
your arch-enemy or you can avoid that encounter altogether.
Hence Darksheer stumbled onto different path previously untraveled
by eddyx or BONEHEAD and that's why he couldn't "walk thru" the game
while directly following solutions.

Actually there are several endings for spycraft. 
While at red square don't do anything, just listen to president's talk.
This leads to alternative ending.
Or you could neglect to shoot Yuri. This moral approach gives yet another
ending. There may be others, I'm not sure, didn't bother to check for 

		Veikko Danilas, maintainer of The Spoiler Centre

The Spoiler Centre