SPOILERS in this comment!! I absolutely love the game! I double every positive comment here. I just want to give feedback on the Scalpel Guy boss battle. Not only is it too long, it is more frustrating than complicated - It is very hard to move you character because of the invisible walls in the room, especially considering they are asymetrical, and I believe it could benefit from a reduction to like 40 seconds.
Aside from that, love this! You are so immensely talented, can't wait for Chapter 4!!!