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