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.
Superseded by OpenTK: https://sourceforge.net/projects/opentk/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Superseded by OpenTK: https://sourceforge.net/projects/opentk/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...
BugEye is an XML-based unit test creation framework. Being XML-based, it can be easily translated to almost any language. The current translations are C#, Java, JavaScript, and Visual Basic. Future translations include C++, Python, Perl, and PHP.
Command Script 4 (CSC4) is an "application control" or application extension scripting language / virtual machine / compiler environment. CSC4 supports object member access, object creation and static calls to the underlying .NET Framework 2.0.
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.)
The Service Invocation Framework ( SIF ) is a framework for stream lining the creation & deployment of .NET Windows Services. It contains all of the plumbing and base classes required to create a windows service from scratch.