It's awesome, and it's free. 
http://www.youtube.com/watch?v=_sxSkiC8EEY
Here is some information about the game -> http://en.wikipedia.org/wiki/Warsow_(video_game)
Here is some information about the Fork of the Quake 2/3 engines used for the game -> http://en.wikipedia.org/wiki/Qfusion
Here is the game download -> http://www.warsow.net/download