A very complete entry. The character controller is finely tuned, I like how deploying the balloon takes into account existing velocity, instead of immediately yanking the character upward, it adds to the skill ceiling.
One thing I'd request would be making the death/restart sequence skippable or much shorter, including the screenfade. Sometimes I died a lot at the start of a level, and I was watching the animation about as much as playing. I'd prefer to just immediately respawn.