There are 3 repositories under mit-scratch topic.
A New Cross-Platform 2D 3D Game Engine
Customize the Scratch website and editor
MIT Scratch e App Inventor - Aprenda a programar de forma simples e divertida usando uma linguagem de programação visual.
An alternate website for Scratch (MIT) that's compatible with old browsers.
A multi-platform aerial combat video game developed on Scratch by MIT and packaged by TurboWarp Packager