I don't know if it's an actual feature, but before I beat the game the square was stuck on accelerate so it became a sort of crash test game. I liked that a lot actually! Then I beat 6, came across another room and when I restarted I could control my speed. Also, the music for levels 3 and 4 is great! Would you mind PM'ing me what it is? Also, the physics in general were done pretty well. Good shtoff!