Call Of Duty: Black Cocks (along with Mafia 2, best game of this year) Condemned: Criminal Origins (literally, sick game, about an FBI agent who got set up by a serial killer)
F.E.A.R. 2 (if you haven't play the first F.E.A.R. do that, cos you won't understand the plot)
S.T.A.L.K.E.R. (I bet you played that game)
Call of Juarez and Call of Juarez 2 (best western FPS on PC right now)
Crysis: Warhead (add-on, one hundred times better than the original)
Prey (I bet you already know that game)
Prince Of Persia: Warrior Within (best Prince of Persia game and best Prince of Persia ever)
Just Cause and Just Cause 2 (nothing REALLY special but muuuuuuuuuuuuch fun)
Painkiller (please, you need to check that game! shit is fun!)