Godot is a powerful cross-platform game engine
One framework for creating powerful cross-platform games
Desktop/Android/HTML5/iOS Java game development framework
Open source HTML5 game framework that offers WebGL and Canvas
A simple and easy-to-use library to enjoy videogames programming
Open source library for creative expression on the web, desktop, etc.
Open Source MMORPG Framework
CTFs as you need them
You can make it - Open Source MMORPG Platform
Gideros Release version
A Complete WebGPU Game Engine for Browser & Desktop Arcade Oriented
Arianne is an engine to develop multiplayer online games like Stendhal
INSTEAD - Simple Text Adventure Interpreter.
Orx: Portable Game Engine
Game engine supporting many 3D/2D formats and graphic effects
JavaScript framework to build game engines, games, emulators and apps
Java Settlers
Cinema Enters Game Console
Cross-platform 2D and 3D game engine
Reactive extensions for Unity
Portable game engine with main focus on point-and-click adventures
Build Cross-platform Applications
Asphyre is a cross-platform framework for Delphi and FreePascal.
Open-source, cross-platform, C++ game engine for creating 2D/3D games