-Bioshock series (everything in this game is good for me)
-Far Cry 2 (GREAT game, you will love it!)
-Metro 2033 (incredible atmosphere)
-Fallout 3 (mix of RPG and FPS)
-S.T.A.L.K.E.R series (mix of RPG and FPS)
-Borderlands (yes, again, mix of RPG and FPS, but you can also play online multiplayer)
-COD games (Modern Warfare, Modern Warfare 2 and Black Ops)
-Half Life series (very good storyline)
-Deus EX series (excelent gameplay)
-System Shock
-The Chronicles of Riddick series