voxeliq 
voxeliq is an open source block-based game engine implementation developed with C#. It uses XNA or the Monogame as the basis. It can be compiled with Microsoft .NET or Mono, which means you can run it on Windows, MacOS, and Linux. Please see the file LICENSE for licensing details.
Code
The last working version resides in contrib/old-codebase
Why?
We would like to develop an open-source and 100% moddable blocky-game which will run on any platform that Mono can. Though we are still far away from being complete which means you are more then welcome to contribute!
Retake?
The project initially started as a hack & slash project and growth un-intendedly. The old-code was quite un-maintainable and buggy (the famous meshing bug!)
- We decided to re-code it from strach with clean comments and tests for all major functionality.
- Dropped support for XNA, the new version will be just use MonoGame as it was quite hard to maintain all platforms together.
- The old code resides in contrib/old-codebase.
Stay awhile and listen
Screenshots
