Godot is a powerful cross-platform game engine
Open source HTML5 game framework that offers WebGL and Canvas
Real Time Strategy game engine supporting early Westwood classics
ThinkPHP Framework
Open Source MMORPG Framework
Gideros Release version
Self-hosted CMS platform based on the Laravel PHP Framework
Arianne is an engine to develop multiplayer online games like Stendhal
Game engine supporting many 3D/2D formats and graphic effects
JavaScript framework to build game engines, games, emulators and apps
Amateur 3D Game Engine
Old-school 2D game engine
Spring is a free RTS engine developed for Windows, Linux and Mac OS X.
FreeCS is a free-software reimplementation of Counter-Strike 1.5.
The imaginary eight-bit machine
Free and Open Game Programming Language for Windows and GNU/Linux
Asphyre is a cross-platform framework for Delphi and FreePascal.
2D game engine for traditional platform games
Open Game Bootstrap
Built to be ease of use, with no programming knowledge, Multi-platform