Oh I don't know. I use to play several games at a time, I never really stayed on one game for long. But I would have to say Halo took up a lot of my time, & Oblivion.
Before the turn of the century though I was all about some WinBack: Covert Operations on the N64. I played that game hours on end trying to beat Duke, the big guy with the chain gun. I still got the game to, haven't really played though, I just have it because it's sentimental.