RetroArch is a frontend for emulators, game engines and media players.
A cross-platform PSP emulator
Godot is a powerful cross-platform game engine
Set of Python modules designed for writing video games
Open source voxel game engine with support for survival and crafting
The game engine for everyone
Mangos ZERO is a server for World of Warcraft
A Minecraft Launcher which is multi-functional, cross-platform
Compatibility tool for Steam Play based on Wine and other components
The Playstation 2 emulator
Xash3D FWGS engine
Sandbox video game with a powerful physics engine
Stream switch games to your PC via USB or network
A simple and easy-to-use library to enjoy videogames programming
UCI chess engine
Head tracking app for games and flight simulation software
Open source HTML5 game framework that offers WebGL and Canvas
Home theater software and entertainment hub for digital media
Desktop/Android/HTML5/iOS Java game development framework
One framework for creating powerful cross-platform games
Open-source Android/Desktop remake of Civ V
The ioquake3 community effort to continue supporting/developing id's
scene-oriented, flexible 3D engine (C++, Python, C#, Java)
Multi-platform Engine for Desktop, XBOX (UWP) and Mobile games
Custom launcher for Minecraft to easily manage installations