Godot is a powerful cross-platform game engine
A simple and easy-to-use library to enjoy videogames programming
Enables Roblox developers to use professional software tools
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 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
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
Gideros Release version
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