Godot is a powerful cross-platform game engine
Enables Roblox developers to use professional software tools
Real Time Strategy game engine supporting early Westwood classics
Open Source MMORPG Framework
A simple and easy-to-use library to enjoy videogames programming
Desktop/Android/HTML5/iOS Java game development framework
Open source HTML5 game framework that offers WebGL and Canvas
One framework for creating powerful cross-platform games
Fast and lightweight JavaScript game engine built on WebGL and glTF
ThinkPHP Framework
Open source library for creative expression on the web, desktop, etc.
lua dev plugin for unreal engine 4 or 5
Self-hosted CMS platform based on the Laravel PHP Framework
Open source library for N64 development
You can make it - Open Source MMORPG Platform
Gideros Release version
A game framework written with osu! in mind.
CTFs as you need them
Arianne is an engine to develop multiplayer online games like Stendhal
INSTEAD - Simple Text Adventure Interpreter.
Game engine supporting many 3D/2D formats and graphic effects
Old-school 2D game engine
Orx: Portable Game Engine
A Complete WebGPU Game Engine for Browser & Desktop Arcade Oriented
High-efficiency minimalist C++ wrapper for OpenGL 4.3