One framework for creating powerful cross-platform games
Reactive extensions for Unity
Portable game engine with main focus on point-and-click adventures
C/C++ , PHP, PYTHON, 3D ENGINES, CHROME NATIVE CLIENT
3D .NET engine for Windows, Linux, Mac
Open Source Virtual World and MMOG Development Platform
Fully fledged steam community SDK
Investigo - DX9 Performance and Debugging Toolkit