Free game engine for development of desktop, mobile, and web games
Desktop/Android/HTML5/iOS Java game development framework
Multi-platform 2D and 3D game engine
Code for Cicero, an AI agent that plays the game of Diplomacy
Source code repository of the FreeOrion project
scene-oriented, flexible 3D engine (C++, Python, C#, Java)
Orx: Portable Game Engine
A free Chess program for Windows with a large set of features
A 2D game engine and level editor
KlayGE is a cross-platform open source game engine
A cross-platform 2D game engine
scriptable game engine with built-in support for 2D graphics and sound
The Atomic Game Engine is a multi-platform 2D and 3D engine
2D ARPG Engine
A traditional top-down OpenGL car racing game
evolution for vegastrike SpaceSim/Combat/Trade game
2D game creation software
A generic 2D engine for any kind of game
2D physics engine for games
Develop an emulated Darkfall Online Server.
Cross platform 2D game creation framework with Python bindings