The movement feels like an ice level or something. Stopping definitely needs more friction or something. Also, usually platformers have variable height jumps - like you can perform a short jump by tapping jump or a longer/higher jump by holding the jump button. I think Mario games achieve that by reducing the effects of gravity on Mario when the jump button is held. The game over and win screens soft lock the game, you might want to have it so hitting any key starts a new game at that point or something.