You have a README which is great (I would fill it out with some more info however), and you'll need a License file (these are two main criteria for open source category).
Graphics are cute, colour scheme is a good choice. This is a really cool concept, balancing between speed and jumping; and perfect for the theme. For the first "level", maybe make it a little easier so the player can get the hang of the control balancing. I would also add some sound effects and music to make it a little more immersive. Physics and controls are great.