This was great fun! Controls took a little thinking about for a couple jumps (mainly because I would typically tap W after my bounce on reflex, causing me to cancel my raise with a hover), but overall it handled really well. My singular gripe is that if you get the underground...thingy last, the game ends before you can grab the last 5 circles. This forced me to restart and go back down so that I could get past the platform that originally held the mysterious sash thing. If there was a place you needed to go (maybe back at the start) once they were all collected to finish, it would fix this very minor inconvenience.
Honestly, great work. I thought I was going random ways, only to find that different paths led to the same places, adding exploration while granting freedom. I had a fun time.