Stride (formerly Xenko), a free and open-source cross-platform C# game
A .NET ascii/ansi console engine written in C# for MonoGame and XNA
Cross-platform 2D game engine focused on ultimate productivity
Svelto ECS C# Entity Component System
Ze Text Adventure game Builder : Create as you play !
Vivid3D is an open-source 3D engine with powerful 2D UI.
2D Game Engine
Portable game engine with main focus on point-and-click adventures