ZweiDe is a game development framework specialized on two-dimensional games. It is based on the .Net environment, OpenGL and irrKlang providing an easy-to-use class complex for graphics, sound, user input, etc. While engine and source code are completely free for any use, the irrKlang library that is used for its sound support may be not. You should check its license separately regarding your own projects aims (commercial / free).
This is the ZweiDe source code release package, containing Visual Studio projects and project templates. The solution and project template has been tested and developed with Visual Studio 2008, it might cause problems using Visual Studio 2010 e.g. .Net 4.0. To fix this, set your starting projects target framework to .Net 3.5 or lower.