BROOOO, WHY YOU TESTING MY MATH? Nah, just kidding — nice game! It would be great if you could choose the difficulty, though. That way, it could even be fun for kids to play, especially those who need to practice math.
Great idea - I would definitely do something like that if I had more time. It's pretty hard to included all the features you want in only 2 days!
You can add it after the game jam. I was just suggesting ideas that could make it better.