I got stuck here... dashing into the crystal doesn't seem to work all the time; there's a tiny boost but not enough to get to the next one. I got frustrated trying to figure this bit out so gave up.
Main issue for me is it feels super awkward to press direction, jump, and dash with 1 hand (plus switch mask on right). Other than that the control feels pretty fair, little bit of physics jank but solid overall.
The levels just get way too hard too quickly xD.
I relied a lot on walljumping up walls celeste-style (walljump without pressing a direction, then going toward the wall...) so I think I cheesed a few sections too. Actually the first thing I did was jump all the way to the top of the game from the first room - I guess in a way I got to the end? xD
Love the artwork and music, the tileset + background for the blue mask (above screenshot ^) is especially nice.