Since it is so hard to find a truly Open Source FPS, here's a list which should clear things up:

Real Open Source Shooters[]

  • FreeDoom - everything modified BSD.
  • Nexuiz - everything GPL (However, the tradmark and engine were relicensed for commercial use)
  • Xonotic - Everything GPL (Based on Nexuiz source code after reliscencing)
  • Open Quartz - everything GPL.
  • Red Eclipse - Based off Cube 2 engine, under zlib, content under Creative Commons Attribution-ShareAlike.
  • Terminal Overload - code under MIT license, content under Creative Commons Attribution
  • Tremulous - engine GPL, content mostly Creative Commons Attribution-ShareAlike.
  • TUER - code source under GPL, artworks without licence

OSShooters somewhere between[]

  • Cube - Partly open source engine (network code is not, neither is the content)

OpenSourceEngine but closed content[]

These games use an Open Source game engine and/or gamecode, but the content is only free as in beer, not freedom in the true sense of the word; they are effectively more like freeware games.

  • AlienArena
  • Argonium
  • AssaultCube
  • Revolution
  • Sauerbraten aka Cube2
  • Warsow
  • World of Padman
  • Wolfenstein: Enemy Territory
  • Smokin' Guns

Freeware (Non Open Source)[]

We'll just list them, as they are not important for our project:

  • Americas Army
  • F.E.A.R Combat
  • War Rock