BZFlag is a 3D, multiplayer, tank battle zone, capture the flag game that pits players against each other in a networked environment. It runs on Windows 95/98/NT/2000, Linux, MacOS 10.x, Irix, Solaris, and others. An OpenGL accelerator is highly recommended, but it is playable with 3D in software.
Mother of all gravity games (Moagg) combines several game genres such as races, search and rescue, seek and destroy, etc. into a 2D gravity game. You are the pilot of a small spaceship, and have to navigate through different levels. Beside the gravity that drags you down, there are other obstacles like magnets, black holes, cannons, rockets, tanks, etc.