RPG Maker 2000/2003 and EasyRPG games interpreter
Voxel game-creation platform with easy modding and game creation
Multi Theft Auto is a game engine
The Ren'Py Visual Novel Engine
Magic Another Game Engine
utility collection for 2D game development in Java; sound-player
Game engine supporting many 3D/2D formats and graphic effects
Full featured MUD server with all the trimmings.
Spring is a free RTS engine developed for Windows, Linux and Mac OS X.
An online multiplayer turn based strategy game and board game engine.
Built to be ease of use, with no programming knowledge, Multi-platform
C++ Text Adventure Engine
Point-and-click 2D game engine
OSGET is the first open source mobile game engine template.
Free MMORPG Engine. Develop and host graphical browser-based games.