: O

Uh, I guess it would have to be...

Quake 3, all expansions, It's just an amazing game, with an awesome load of mods, and I've just come off playing it for about an hour, (I totally wasn't using timescale 0.25) xD

And I keep getting progressively better.. What would make Quake 3 better, is that if it got hi-def graphics all of a sudden..........