I really like the concept and overall had fun. I love the idea of singing notes to the gates in the correct order to continue. The tutorial text at the start seemed to disappear too quickly to read, it would be nice if intentional player interaction was required to dismiss them. I also found the spinning level finish animation to be quite dizzying. Other than that, the only thing I would add is some more interesting levels with different obstacles, as the bubbles weren't too challenging.