Stride (formerly Xenko), a free and open-source cross-platform C# game
One framework for creating powerful cross-platform games
The Open Toolkit library is a fast, low-level C# wrapper for OpenGL
Kubok16 is a math puzzle similar to Sudoku.
Vivid3D is an open-source 3D engine with powerful 2D UI.
Modern 3D engine and IDE written using C# and C++.
3D .NET engine for Windows, Linux, Mac
Android, DOS, FirefoxOS, Linux, MacOS and Windows all in one..
XNA based game engine completely written in c#
An expanded XNA game creation framework
My fork of Manic Digger
Free open source game created in Unity 3d for Windows 64 bits
Open Source Virtual World and MMOG Development Platform
RPG Games without coding!