AgateLib - Awesome game and tool engine library. A platform independent .NET library for developing games and game development tools. AgateLib is built on a driver-based model so that new platforms and rendering pipelines can be implemented easily.
Xilon Engine II is a graphics/game engine written in Visual Basic .NET to allow easy and fast development of ideal 2D games. With XEII, 2D games become more fun for a hobbyist programmer instead of a chore.
ZCore is a set of Creative Studio for designing, testing, building ... solutions based on .NET framework. Contains UML designs tools, code editor & build tools, debug & test tools, user interface create tools ...
Superseded by OpenTK: https://sourceforge.net/projects/opentk/
The Tao Framework for .NET is a collection of bindings to facilitate cross-platform game-related development utilizing the .NET platform.
Superseded by OpenTK: https://sourceforge.net/projects/opentk/
This project aims at writing a threaded, object-oriented and scriptable game engine targetting the .NET platform, using a mixture of c# or managed c++ ports of famous c/c++ components such as OGRE, CEGUI, Newton, Lua, Python, Audiere, OpenAL, etc...
This project will create reusable objects that can be used in game engines to reduce development time. (Development for the 1.1 framework based version has ended.)