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