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