Honestly I'm blown away by how good that was! Short indeed but incredibly fun. It's so easy for platformers to just not feel good, but your control scheme is perfect and it feels incredible.
Costume swap powers were all super unique and fun to play with. Kind of reminded me of Micky's Magical Quest back on SNES. Editing to say I did run into a black screen issue on my first playthrough. I think it was from my pressing escape assuming it was a pause function. Couldn't find a way to recover that without refreshing the page.