This game is excellent and best of all its free.
Not your run of the mill 80's throwback freebie but a game with an unreal type engine.
You have to set up an account to play so you can save your stats but its nothing heavy.
You also have to go through some basic training before you can play online.
Downside is if you're on 56k then it'll take a couple of days to download at over 200 meg