The scroll opening/closing on the title screen is really cool. That little animation immediately gave this game some charm. I also really liked the overworld. Walking between the portals and getting bits of tutorial/story there instead of a big info dump was smart. Was way funner then just having a list of levels.
Mechanically, it's strong. Each plane feels distinct, and you build on mechanics instead of just swapping them out. The gravity plane was probably my favorite, especially once you realize you can flip it yourself. The cave one though, yeah that one keeps you on your toes lol.
Music fits well and the SFX give good feedback when switching planes. This is a really solid puzzle platformer. You can tell a lot of thought went into how the mechanics interact.