Not a very long list here, I'm not that much of a gamer.
World of Warcraft. Really, not much chance of playing
less than 100 hours...
Mass Effect 2, most likely.
Tomb Raider, if you count all of the games as one. Even if not, I must've spent way over 100 hours on the Level Editor alone.
Command and Conquer Generals, as with above, spent a lot of time modding this game.
As for some more unusual games:
Little Big Adventure 2 [http://en.wikipedia.org/wiki/Little_Big_Adventure_2]. I have no idea how often I finished that game, but me and my sisters were crazy about it for years. Even tried to recreate the game's world in Rollercoaster Tycoon at some point.
Supaplex [http://en.wikipedia.org/wiki/Supaplex]. Crazy puzzle games, what a way of growing up...
Suki the Cat said:
People actually
play that? And for no less than 100 hours? You must've been supremely bored
[sub](/joking)[/sub]