Stars
Yet another 2d game engine of dreams (work in progress)
Powerful independent cross-platform engine for 2D/3D games and visualizations. Young, strong and crazy!
Saddy is an open-source crossplatform 2D graphic engine, based on OpenGL, which can be used for creating 2D games. like platformers or RPGs.
One framework for creating powerful cross-platform games.
An example for accessing C code from a Xamarin app. http://kerry.lothrop.de/c-libraries
CocosSharp is a C# implementation of the Cocos2D and Cocos3D APIs that runs on any platform where MonoGame runs.
Tools and libraries to glue C/C++ APIs to high-level languages