PunchLab - Track the strikes you throw at the punching bag
Xonotic - Xonotic is a free (GPL), fast-paced first-person shooter that works on Windows, OS X and Linux.
Timerly - A real interval timer
Counter-Strike - Counter-Strike is a PC-exclusive FPS video game developed by Valve Corporation.
Liteboxer - An at-home boxing solution
Quake - Quake is a series of first-person shooter video games released by id Software.