Orx: Portable Game Engine
RTS game with the theme of Strategy by Design
GemRB is a portable open-source implementation of the Infinity Engine
Arianne is an engine to develop multiplayer online games like Stendhal
Zoomable user interface (ZUI) with file manager, file viewers and more
Old style soccer game with many exciting features
Game engine supporting many 3D/2D formats and graphic effects
DOOM / Heretic / Hexen source port with enhanced graphics and UI
portable o2em launcher
Low-Level Game Engine for Retro Platforms
Portable game engine with main focus on point-and-click adventures
SJCE - free portable cross-platform graphical chess game, 100% Java.
Multi-System Emulator
scriptable game engine with built-in support for 2D graphics and sound
3D video music media player lyrics subtitles etc...
distraction-less card game
Sims 3 (and other) game package library
Fast and robust map analyser for Brood War.
Multi-platform game engine similar to old Megaman with a stage editor