A .NET ascii/ansi console engine written in C# for MonoGame and XNA
The Open Toolkit library is a fast, low-level C# wrapper for OpenGL
Stride (formerly Xenko), a free and open-source cross-platform C# game
API (C#) for simulating certain aspects of a ZX spectrum for porting.
2D Game Engine
XNA based game engine completely written in c#
WGFX 2D Game Engine