Java Settlers
Spring is a free RTS engine developed for Windows, Linux and Mac OS X.
Cinema Enters Game Console
Modern 3D engine and IDE written using C# and C++.
A Project which shall result in a Remake of the classic game
A 2D game engine and level editor
Mad Vandal's FortressCraft Mod Source Code
Cross-platform 2D and 3D game engine
8-bit Graphical API for Java
Source code of the chapters of the book 3D Game Development with LWJGL
CSG for jMonkey
Example code for creating a 2D platform game in Java.
Portable game engine with main focus on point-and-click adventures
Vivid Engine 2 is an open source 3D Engine coded using C# and C++.
C/C++ , PHP, PYTHON, 3D ENGINES, CHROME NATIVE CLIENT
Lego Island 2 Game Editor
2D ARPG Engine
Perl bindings to the Modern OpenGL API
Open-source, cross-platform, C++ game engine for creating 2D/3D games
3D .NET engine for Windows, Linux, Mac
Gaming library