Clock said:
Forget the first game even existed. For it is shite.
Timesplitters 2 however is very good and there is absolutely no need for the first game that you should have forgotten about by now already.
I must admit that I only have it for Xbox, but I believe all versions are the same.
I got TS2 for the GameCube, and it was very good.
I then went back and got TS for PS2. Not shite per se, but less polished by far. Still, I enjoyed the missions, and it was cool to see where some of the deathmatch and challenge boards in TS2 came from...but the story in TS is well-nigh non-existent...TS2 has a tiny bit more of a story, but even it is just the shallowest excuse to make a great FPS that takes place over a bunch of different historical (and futurical) setting.
Get TS2. If youy really enjoy the missions a lot, consider getting TS for cheap, but don't get your expectations too high.