Sauerbraten First Person Shootem
Sauerbraten (a.k.a. Cube 2) is a free multiplayer/singleplayer first person shooter, built as a major redesign of the Cube FPS.
We have been advised the game can be very hard to catch onto, as it uses unique gameplay, but this is very rewarding. Nexuiz, unlike the other FPS's, this has extremely complex graphics. We can not comment on how good or bad (bad as in good) it is, this is something you need find out for yourselves, perhaps more skill is required for this game.
A Word About Games
Many people are frustrated for want of a better expression with Linux because they think it is lacking in the Games department, all said and done this is not an accurate assessment. Want to know what Gutsy Gibbon support by way of games just look here Intrepid Ibex Games and Ubuntu Community Docs Games