Left 4 Dead (and L4D2)

So, a few of the games that my pc can play, are Left 4 Dead and the sequel, I've just bought them through steam (after beating Half life (and ep's) a couple of times on all the different difficulties), and I'm truly excited to play these. I've heard a lot about them, and I expect a somewhat good experience from them.

I heard they're supposed to be difficult to beat, but then again, the same was said about HL2 by the people who told me this.

Oh!.. I love stressy FPS games, only thing I love more, is stressy horror survival games.

FEAR was decent, Fallout didn't have much, HL2 was literally fun more than spooky (I got the headcrab plushtoy, maybe that's the reason), I'm hoping that this will be good at giving me some spooks. Or that games such as Dead space, which I intend to play once the new laptop arrives, will do this for me.