you could get Oblivion, Might and Magic, and Gothic 3 if you like the more open ended rpg type games. If you like RTS games, then I would recommend Company of heroes, Nexus: the jupiter incident, and Star wars: Empire at war. If you like GTA style games, I would recommend GTA: San Andreas, and Just cause. If you like Sim games, the the Sims 2+one of there 732 expansions
, or The Movies. Finally, with shooters, I would recommend Counter strike source, Half life 2, Day od Defeat Source, Half life 1: source,Call of duty 2, Star wars republic commando, F.E.A.R (only if you like crapping your pants, though), Doom 3 and Quake 4 are pretty dark, and so is Prey, but if your fine with that, go for it. Far Cry is also a pretty sweet FPS.