Multi Theft Auto is a game engine
Open 3D Engine (O3DE) is an Apache 2.0-licensed multi-platform 3D
The ioquake3 community effort to continue supporting/developing id's
A multi core friendly rigid body physics and collision detection lib
Multi-platform Engine for Desktop, XBOX (UWP) and Mobile games
Kotlin extensions for the libGDX game framework
3D and 2D game engine written in Rust
The HTML5 Creation Engine
LayaAir is an open-source 2D/3D engine
A modular Common Lisp game engine
The game engine for everyone
Multi-platform 2D and 3D game engine
The Tiny JavaScript Game Engine That Can!
Cross-platform 2D and 3D game engine with modular architecture
Voxel game engine in C++ with OpenGL
A Flutter based game engine
dhewm 3 main repository
Fast and lightweight JavaScript game engine built on WebGL and glTF
Open source clone of the Age of Empires II engine
Free game engine for development of desktop, mobile, and web games
A refreshingly simple data-driven game engine built in Rust
Magic Another Game Engine
Stride (formerly Xenko), a free and open-source cross-platform C# game
scene-oriented, flexible 3D engine (C++, Python, C#, Java)
Open source library for creative expression on the web, desktop, etc.