dsi is a simple game of invading aliens. You must stop those aliens from landing on you. It features smooth scrolling, high scores, 5 levels, simple controls, sound effects, and user selectable music. Working joystick support. Watch out for the tenacious mega! The graphics can be customized out of the box without requiring any recompiling. A simple definition file can be customized for coders.
swampex (or Swamp Explorer) is a cross-platform library designed to work with raster maps in Ozi Explorer format. Using this library, you'll be able to collect maps in the file system, get information about map calibration, find maps by latitude/longitude, render maps in SDL surfaces, and more.
ioquake3 (or ioq3 for short) builds upon id Software's Quake 3 source code release. It cleans it up, fixes bugs, and adds features. Its goal is to be the Quake 3 distribution upon which people base their games and projects. Its design goals include optimizing the engine for playing Quake 3: Arena, Team Arena, and all popular mods. This distribution of the engine has been ported to many new platforms. While it doesn't have PunkBuster (and never will), it does provide more security for servers and clients by way of various bugfixes which aren't in id's client.