Love the concept and the execution, but it was too challenging for me... I wish the puzzles ramped up a little more slowly. If I'd gotten stuck on the "M" level instead of the "J" one, I might have stuck to it for longer to try and get through it.
The graphics and audio fit perfectly, though. And finally figuring out the different puzzles (or finding out that they were impossible) was rewarding and amusing. Wish I'd had the platforming skill to get all the way to the end.
Great job!