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.
BotBoxer - A first ever robotic punching bag with computer vision
Counter-Strike - Counter-Strike is a PC-exclusive FPS video game developed by Valve Corporation.
Timerly - A real interval timer
Quake - Quake is a series of first-person shooter video games released by id Software.