I'm really excited about Clear Sky, I'm hoping for some real polish to a game that's a true diamond in the rough.
I notice lots of people claim this game isn't open ended, I beg to differ, while the role playing aspect is not as open ended as we'd like, the tactical part is open ended. Right from the very first mission you can choose how to proceed in rescuing the STALKER in the village. You can run and gun, try to sneak around the back, etc. Being able to do this is very cool and is more interesting than say Call of Duty 4 where you have very little choice as to what happens. I'm in no way saying what CoD4 does is bad, it isn't, it does what it does very well but to say that STALKER isn't open ended is a gross misrepresentation of the game.
Someone asked me what STALKER was like, I said it was like single player BF2 with some minor role playing elements thrown in. It's more shooter than RPG and when you look at it that way STALKER is very open ended.