UCI chess engine
Godot is a powerful cross-platform game engine
An open-source sandbox tower defense game
Stream switch games to your PC via USB or network
A cross-platform PSP emulator
A simple and easy-to-use library to enjoy videogames programming
Xash3D FWGS engine
A certain block game
Desktop/Android/HTML5/iOS Java game development framework
Sandbox video game with a powerful physics engine
RetroArch is a frontend for emulators, game engines and media players.
Home theater software and entertainment hub for digital media
The game engine for everyone
Open source voxel game engine with support for survival and crafting
Open source HTML5 game framework that offers WebGL and Canvas
One framework for creating powerful cross-platform games
Voxel game-creation platform with easy modding and game creation
Do virtual gear shifting (and more) in any rider app
Open-source Android/Desktop remake of Civ V
An open source reimplementation of the Among Us Server
scene-oriented, flexible 3D engine (C++, Python, C#, Java)
Netcode that provides networking capabilities to GameObject workflows
Cocos simplifies game creation and distribution with Cocos Creator
The source code to VVVVVV
Multi-platform 2D and 3D game engine