Open source HTML5 game framework that offers WebGL and Canvas
3D game engine/framework in C, with Luajit and Python bindings now
Self-hosted CMS platform based on the Laravel PHP Framework
CTFs as you need them
Open source library for creative expression on the web, desktop, etc.
JavaScript framework to build game engines, games, emulators and apps
Framework for producing web-based database applications
A completely free, open-source, 2D game engine
Javascript library for making tile based games
XML-based framework for developing games
The imaginary eight-bit machine
A complete web framework to create online Fighting Fantasy adventures
Massively multiplayer online game server and client framework
Bring web-cam to life on your monitor.
3D .NET engine for Windows, Linux, Mac
Turbulenz is a modular 3D and 2D game framework
Mud Server in Python Language playable via web browser
Educational framework for OpenGLES, OpenCL and OpenAL
Android:Netrunner Tournament Manager
Modular Gaming Open Source Persistent Browser Based Game Framework
XMICAE is a framework for browser-based IF/RPG narratives.