Blazium Engine is a free, open-source fork of Godot for building cross-platform 2D and 3D games and applications, with the tools, platform integrations, and improvements you need.

ECS based game engine originally created for space station 14 but other games are supported. It is intended for multiplayer games and it is possible to sandbox the client.

s&box is a spiritual successor to Garry’s Mod, using Source 2 to create a modern, intuitive, moddable game development environment.

A free and open-source 2D and 3D cross-platform game engine that can be used to create video games for PC, mobile devices and virtual reality or interactive content.

Gondwana is a cross-platform 2.5D game and rendering engine written in C#/.NET 8, built with SkiaSharp for graphics. It modernizes legacy Win32/GDI patterns into a modular, high-performance framework that runs on desktop, mobile, and web.

An engine designed for development teams (C++/C# programmers, 3D artists) working on interactive 3D apps

A custom-made game engine based on the Raylib Framework. The Main focus is being performant and only using draw functions instead of textures. When using Shape Engine everything from Raylib is available as well.

FNA is a reimplementation of the Microsoft XNA Game Studio 4.0 Refresh libraries

Prowl is an open-source, MIT-licensed game engine developed in pure C# in latest .NET. It aims to provide a seamless transition for developers familiar with Unity by maintaining a similar API while also following KISS and staying as small and customizable as possible. Ideally, Unity projects can port over with as little resistance as possible.

Redot Engine is an open source fork of Godot with the goal of fulfilling the promise of Godot.

KNI, a fork of Microsoft's XNA Framework, is a simple and powerful .NET framework for creating games for desktop PCs, Mobile devices, Virtual Reality headsets and the Web, using dotnet framework & the C# programming language.

NeoAxis Engine is a versatile real-time platform for making 3D, 2D games and apps

A free, all-in-one, cross-platform game engine that makes it easy for you to create 2D and 3D games.

A full-source code available and agile game engine

A framework for cross-platform games

A simple and easy-to-use framework for writing small games and prototyping in C#.

A cross-platform game engine used worldwide. The engine can be used to create three-dimensional (3D) and two-dimensional (2D) games, as well as interactive simulations.

RPG Architect is a next-generation RPG game maker with all of the limitations removed. It is designed to be simple enough for a newcomer and advanced enough for a veteran of game making engines.

A game development platform built in C#

A pixel art ECS game engine built on top of MonoGame.

A powerful game development platform to create world-class entertainment experiences

The graphics development engine for business and industry

Free cross-platform 3D game engine with C# scripting, Bullet physics and OpenAL audio

An in-development experimental fork of Urho3D game engine