Civ, Age of Empire series, SC/WC, Dota, LoL, Diablo, Titan Quest, ME Series, Elder Scrolls Series, the Fallout series, a bunch of diffrent simulations like Transport Tycoon, everything Maxis spits out once in a while or Tropico, Gothic 1+2.
There are a bunch of them actually. There has to be variation in the way you solve your problems, diffrent endings, or in the case of multiplayer games alot of strategic/tactical depth.
Singleplayer games outside the RPG's kinda fall flat for me though. I wouldn't even have played ME multiple times, if there werent multiple paths to experience the story.
Most of the time it's either trying something new or perfecting something you already did.