Only went through about one playthrough, but I really enjoyed what I ended up trying here. I definitely recommend at least fleshing out what you have into a differently titled game once more progress is put into it.
Movement overall felt good, but not fantastic. Just a little slidey for my liking personally. I also felt like eventually you should try and implement a flutter jump as it might help in a 3D environment in the same way as the 2D game. It was super cute and I know it's just you slowly working on it so I can't expect crazy amounts of polish. I LOVED the rocket jump mechanic as I'm a huge fan of momentum in platformers.
I really, really liked it and I hope you keep working on stuff :)
(Also you should totally add 20 more crystals to make the total a solid 100 (: )