This is a joyfully simplistic game. It's amazing how much awesome designing you were able to do with just the basic mechanic of jumping (ignoring that second cat section because it's been talked about enough, and I agree with the public sentiment on its difficulty).
Obviously the art could've been more fleshed out, there could've been more animations and particles, there could be more music and there could be more game content, but the game needs none of that! In essence, it's complete, and, as I tried to avoid mentioning until now, it's so impressive that you managed to do that in just four days.
Phenomenal game!