Thanks for considering contributing to the project!
First off, before you start forking and making changes for a pull request, be sure you understand the purpose of the sandbox. This is for introductory programming students to be able to explore interesting physics simulations.
This is not a toolset for programming a game, even though you can program one in it (good luck deploying it, though!)
Pull requests that match the existing API style will be looked more favorably upon than ones that depart radically from it.
Keep tutorials basic. We want students to push their own boundaries, and not just copy and paste tutorial code. Tutorials should show basic concepts, but not put it all together into a complete project.