Cool! That's a good plan!
I wouldn't worry too much on the art style right now, you can always tweak it later.
And about the license requirements, read into them carefully. But basically, the requirements for this jam is for your project to be completely open source and free to modify and distribute. Any modifications made to your project by another developer must also follow the same requirement: open source and free to modify and distribute.
I'm bringing attention to that, because not everyone wants to put out their projects like that, as free software. If that's not your intention, then this jam might not be for you.