Kotor
 

I would have to say that this is the best game on Xbox currently.. you start out as a minor soldier on the Endar Spire, and work your way up to a Jedi. Right now, I'm on dantooine so I haven't gotten TOO far, but I am also doing all the side quests too.

I have played it a bit, it doesn't beat Halo but it sure is sweet.

I beat it the week it came out. Fucking great game.

I beat it one darkside first with a 30 hour save game then started new game and did light side on a 40 hour save game... I guess killing everyone instead of questing is quicker hence the shorter time.

[edit] oh and yes as a singleplayer game it is better then Halo in my opinion... but no multiplayer so not that much longevity =(

I beat Light Side two times both in like 30ish hours dark side took around 27 hours (only beat dark side once)