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
Desktop/Android/HTML5/iOS Java game development framework
Real Time Strategy game engine supporting early Westwood classics
One framework for creating powerful cross-platform games
Open source HTML5 game framework that offers WebGL and Canvas
Fast and lightweight JavaScript game engine built on WebGL and glTF
Open Source MMORPG Framework
CTFs as you need them
lua dev plugin for unreal engine 4 or 5
You can make it - Open Source MMORPG Platform
Gideros Release version
ThinkPHP Framework
A game framework written with osu! in mind.
Unity3D Client And C# Server Framework
Self-hosted CMS platform based on the Laravel PHP Framework
Open source library for creative expression on the web, desktop, etc.
Arianne is an engine to develop multiplayer online games like Stendhal
All-In-One program that combines multiple Fortnite Dev Account tools.
Game engine supporting many 3D/2D formats and graphic effects
An isometric arcade-style game of skill, puzzles and exploration
Old-school 2D game engine
Orx: Portable Game Engine
JavaScript framework to build game engines, games, emulators and apps