A truly extensible cross-platform game engine
Convert Ren'Py visual novels into a format your ebook-reader knows
Allows the Sourcemod FunCommands to be limited
An open source skateboard games engine written in C# and .NET.
3D Web UI, Embed Web and Flash in 3D Games, based on WebKit
Pear3DEngine is a modern and modular 3D development framework
Open Source Virtual World and MMOG Development Platform
Phobos editor is a generic resource editing system.
An open source C++ console based game (Windows only).
C++ Game programming Framework
cross-platform 2d game engine
I am working on upgrading the XNA Platform Game Template.
big map framework using Irrlicht
Cross-platform reimplementation of AMOS BASIC (runtime)
Fully fledged steam community SDK
Investigo - DX9 Performance and Debugging Toolkit