RetroArch is a frontend for emulators, game engines and media players.
A cross-platform PSP emulator
The game engine for everyone
Set of Python modules designed for writing video games
Mangos ZERO is a server for World of Warcraft
Compatibility tool for Steam Play based on Wine and other components
The Playstation 2 emulator
Multi-platform Engine for Desktop, XBOX (UWP) and Mobile games
scene-oriented, flexible 3D engine (C++, Python, C#, Java)
Open source library for creative expression on the web, desktop, etc.
New Godot bindings for Swift
The ioquake3 community effort to continue supporting/developing id's
Mod manager for the video game RimWorld
C# application with primary purpose of farming Steam cards
Homebrew development library for Nintendo 3DS/Horizon OS user mode
ThinkPHP Framework
Stride (formerly Xenko), a free and open-source cross-platform C# game
dhewm 3 main repository
Inspecting and manipulating NBT as a file system
3D Engine c++
An Ubuntu remix for both new and experienced Linux sophisticates
A MUD client for Android, iOS, Linux, Mac OS X and Windows
kernel mode mouse accel