I came across a game on a Linux distro and thought it was great – I headed off to the website – sauerbraten and it is available for :

CTF Edition (June 17, 2008):
WindowsDownload for Windows – 292 MB
LinuxDownload for Linux – 301 MB
MacOS XDownload for MacOS X – 306 MB

Best way to describe this game – a Freeware Single/Multi Player that is a lot like Doom or Quake. There is also a Server lister and many maps & Add-ons for this from various sources.

Sauerbraten

Sauerbraten

It can be run inside a window, full screen or anything inbetween and I personally think it is great, the AI is not that hot and easy to pick off the enemies on single player but it’s fun none the less.