Cross-platform 2D and 3D game engine with modular architecture
Multi-platform Engine for Desktop, XBOX (UWP) and Mobile games
The Ren'Py Visual Novel Engine
Cocos simplifies game creation and distribution with Cocos Creator
s&box is a modern game engine, built on Valve's Source 2
Cross-Platform C++ 2D/3D game engine
3D engine with modern graphics
An OpenGL RTS game engine written in C
Multi-platform 2D and 3D game engine
UZDoom is a feature centric port for all Doom engine games
An unofficial rules engine for the world's greatest card game
Stride (formerly Xenko), a free and open-source cross-platform C# game
3D Game engine with editor
A completely free, open-source, 2D game engine
Powerful, mature open-source cross-platform game engine for Python
Multi Theft Auto is a game engine
Free game engine for development of desktop, mobile, and web games
3D Engine with Blender Integration
Cross-platform 2D game engine focused on ultimate productivity
Open 3D Engine (O3DE) is an Apache 2.0-licensed multi-platform 3D
Cross-platform, open source, and super fast MUD client with scripting
A modular Common Lisp game engine
A re-implementation of Freelancer
Open source clone of the Age of Empires II engine
Voxel game-creation platform with easy modding and game creation