Welcome to my Android remake!
Good news! This project is completely open source, and created in a fork of scratch, Penguinmod, where you program using blocks instead of actual code.
The source code can be found here, along with all the older versions.
You need to head here, and clone the repository. After that, head to the catalog folder, and start modifying the files. Make sure to enter your own repository name and your username into AllayOS, and restarting the app should show the files.