Godot Engine - Feature-packed 2D and 3D open source game engine.
RPG Maker - Make your own PC game with RPG Maker. Our easy to use tools are simple enough for a child, and powerful enough for a developer. Try it free today!
FPS Creator Classic - We specialise in game creation tools for a range of devices such as Windows, iOS, Android. With game making tools like GameGuru, AppGameKit, FPS Creator and Dark Basic Professional you can make all types of games.
MonoGame - MonoGame is an open source implementation of the Microsoft XNA 4 Framework.
Stride Game Engine - Stride is an open-source 3D Game Engine written in C# and released under the MIT License that allows you to build powerful game worlds for free or to generate income.
FlatRedBall - Cross-platofrm 2D game engine using C#, focused on developer productivity, transparency, scalability, and ease of use.