The Ren'Py Visual Novel Engine
An updated version of the classic "Basic Computer Games" book
Multi-platform Engine for Desktop, XBOX (UWP) and Mobile games
Cross-platform 2D and 3D game engine with modular architecture
Free game engine for development of desktop, mobile, and web games
Doom-based AI research platform for reinforcement learning
A lightweight game server framework implemented with Actor Model
Kitty-Tools is a Kahoot Cheating Client for all devices and interfaces
Stride (formerly Xenko), a free and open-source cross-platform C# game
Multi Theft Auto is a game engine
A completely free, open-source, 2D game engine
Open source clone of the Age of Empires II engine
Multi-platform 2D and 3D game engine
Cross-platform game engine in Rust
Futuristic Luau for every universe
A dead simple 2D game engine for Go
FlightGear Flight Simulator: free open-source multiplatform flight sim
A planetarium software that shows a 3D simulation of the night sky
A MUD client for Android, iOS, Linux, Mac OS X and Windows
3D modeler, 3D game maker, 3D demo maker
Delphi Java - VRCalc++ OOSL (Script) and + (Binary Exec Distro)
A cross-platform, open-source, pure C game engine for mobile game
A Rust framework for building Minecraft servers
Lightweight Shaders for Intel HD Graphics - (Chocapic13' Shaders edit)