Fallout 3 and New Vegas, S.T.A.L.K.E.R, Supreme Commander, Katamari, Perfect Dark, the oldschool Sonic games, Kirby games, Pokemon games, Star Wars KOTOR series, Black and White 1 and 2, Dungeon Keeper 2, The Sims games, Ragnarok Frontier (Yes, I am THAT geeky!)... I could go on forever, actually.
I am currently hooked on Metro 2033 and Sins of a Solar Empire. I also looooove freeware games. They're often much more interesting than cliched mainstream games. The minimalism of them is a big part of the charm, for me...
If you haven't played Minecraft, GET IT! It will steal your life away! I've spent countless hours building a fortress which spans from the top of a mountain to a dungeon at the center of the world. Next step is to set up booby traps .