These r some of my favorites
FPS: Far Cry, Half Life 2, Chronicles of Riddick (I wont recommend DOOM 3)
Adventure/RPG: POP series (Oblivion 4 though havent played it, it needs bomb of a PC)
Sports: Pro Evolution Soccer 5 ( Avoid EA sports at all costs)
RTS: AOE 2 (old game still rocks, Avoid...