You are captain of the cargo ship Chromium B.S.U., responsible for delivering supplies to our troops on the front line. Your ship has a small fleet of robotic fighters which you control from the relative safety of the Chromium vessel. Chromium B.S.U. is a fast paced, arcade-style, top-scrolling shooter. It uses OpenGL for graphics, OpenAL/SDL_mixer for sound effects, GLC/FTGL for text rendering, and glpng/SDL_image for texture loading.
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.
Zelda2D is a Zelda related fan-game. It is a classic jump'n'run game in the style of Zelda, featuring Link collecting rupees and defending against evil opponents. The game itself is a game engine that reads levels from XML files. It's very easy to write your own levels and to design objects in the game.