Fun game. To really uump it up more try adding some sound effects. I really like how the buttons are matched with the height of the ramp by ordering from low to high.
Love that you have kids test it lol. AS DO I ... I have a game that isn't on Itch.io that is similar to this but with planes. I would love to bounce ideas with you or come up with something. I think I could help you with appearance of the game as well. This is a great idea!