Official binding of SFML for .Net languages
Vivid3D is an open-source 3D engine with powerful 2D UI.
A low-level, portable graphics library for .NET
Modern 3D engine and IDE written using C# and C++.
a 2D Game Development Framework
Arengu is a free 2D RPG with a thrilling story and exciting gameplay.
Isometric engine for 2D rendering with XNA and SDL