Vivid3D is an open-source 3D engine with powerful 2D UI.
Modern 3D engine and IDE written using C# and C++.
A Topdown Zombie Survival in C# and SFML
Exciting Tic Tac Toe game full of features
A Fighting Game
XNA based game engine completely written in c#
Retro Pong .NET, yet another Pong
WGFX 2D Game Engine
A 2D Side Scrolling Platformer Game