Open source clone of the Age of Empires II engine
Powerful, mature open-source cross-platform game engine for Python
Solar2D Game Engine main repository (ex Corona SDK)
scene-oriented, flexible 3D engine (C++, Python, C#, Java)
3D Game engine with editor
Flax Engine, multi-platform 3D game engine
dhewm 3 main repository
3D Procedural Game Engine Using OpenGL
GemRB is a portable open-source implementation of the Infinity Engine
Vivid3D is a C++ IDE/3D engine, with python scripting.
Orx: Portable Game Engine
Multi Theft Auto is a game engine
Urho3D Game engine
A fork of dhewm3 with an emphasis on modernisation and vanilla Doom 3
Spring is a free RTS engine developed for Windows, Linux and Mac OS X.
DOOM / Heretic / Hexen source port with enhanced graphics and UI
Improved version of the X-Ray Engine, the game engine
A 2D game engine and level editor
KlayGE is a cross-platform open source game engine
A cross-platform 2D game engine
Game engine for playing tomb raider 1 - 5 levels.
scriptable game engine with built-in support for 2D graphics and sound
The second demo of my game engine.