In no particular order:
Dom3, Disciples 2(the GOLD edition for this game is pure addiction), Ratchet & Clank series for PS2/PS3(gotta love those),
Earth 2160(I was heavily addicted to this game for a while), Total Annihilation(a true classic and an important lesson in RTS history), Total Annihilation: Kingdoms(TA with a fantasy twist), Morrowind(a great game...once you acquire a few mods that is), Two Worlds, Europa Universalis 3(a very good game... although you get kinda bored after playing it for too long in one session).
Oh, I almost forgot: Banjo-Kazooie series for N64(that's right, I'm a platformer geek. Sue me
