I love the idea that the soundtrack is just the tune which the character hums to himself.
The idea that the player has to be in a certain place to scale an object is interesting. One thing I would like to see more of are situations where it's hard for the player to not scale an object with him (for example if there is not enough space to move away from it or with a separate mechanic) and what kind of puzzles can be created from it.
Great job!