A traditional top-down OpenGL car racing game
Open Source 3D Game Engine
Free strategy browsergame engine.
Multimedia asset management and manipulator for Étoilé
A 2D Adventure Game & Engine
C++ game libraries plus server.
A generic 2D engine for any kind of game
The free and Open Source hockey simulator
LAIR is a Sandbox Dungeon Crawling Game
Library for creating turn-based games with simultaneous moves.
Modular Gaming Open Source Persistent Browser Based Game Framework
TurboSphere is an easy to learn and powerful JS based game engine.
Take the chess graphism, and use it with a chess engine.
Classic backgammon in fantasy setting with a lot of missions.
Pygrid is an open-source and cross-platform pygame/python 2D engine.
Cross platform administration tool for Source Engine dedicated servers