Mangos ZERO is a server for World of Warcraft
A cross-platform PSP emulator
Cross-platform 2D and 3D game engine with modular architecture
Cross-Platform C++ 2D/3D game engine
Powerful, mature open-source cross-platform game engine for Python
Voxel game-creation platform with easy modding and game creation
Free and open source real-time strategy game
Cocos simplifies game creation and distribution with Cocos Creator
Recreation of the classic Grand Theft Auto III game executable
Open Source MMORPG Framework
Tool to statically recompile N64 games into native executables
Multi-platform Engine for Desktop, XBOX (UWP) and Mobile games
Desktop/Android/HTML5/iOS Java game development framework
An unofficial PC port of the Xbox 360 version of Sonic Unleashed
Stream switch games to your PC via USB or network
Descent 3 by Outrage Entertainment
Classic 2D side-scrolling platformer game
Free game engine for development of desktop, mobile, and web games
3D Procedural Game Engine Using OpenGL
Voxel game engine in C++ with OpenGL
Open source clone of the Age of Empires II engine
OptiScaler bridges upscaling/frame gen across GPUs
A free/open source client and automation tool for Ragnarok Online
Self-hosted game stream host for Moonlight
The game engine for everyone