Alien Arena is a free online FPS first person shooter game that can be run from a portable USB drive. It takes a few of the best aspects featured in such popular games as Quake III and Unreal Tournament and then further combines them with unique and original ideas.
Nexuiz is another great free first person shooter game. As opposed to some other well known 3D first person shooters, this FPS game looks and plays great and has outstanding graphics.
