Looks really nice! I found it quite hard, but not in a way that felt unfair, more so in a way like I am terrible at it. Despite this, I just kept playing again, which is a great sign! There was something really satisfying about discovering more and more of the map and thinking out which dimension it made the most sense to do which parts from.
Controls maybe felt a teeny bit off. I think just tweaking some numbers would probably clear it up. But I wouldn't take my word for it if no one else thinks so; platformers are far from being my area of expertise and I think things like that can be quite subjective anyway.
Just a thought with no effect on my rating: I think this would benefit from forcing the player to read the "How to Play" and "Important Stuff," or at least sticking them in the game's description. I'm a big dummy (as many of us are), and went in at first without reading either. I was totally confused and just kept dying with no idea why. Reading both those screens cleared it up easily. Put them somewhere where big dummies like me will have to look!
Overall, really nice! This is one I might want to come back to; I'd love to get to the end of it, but I feel like it'd take me forever because of how terrible I am. Maybe checkpoints or something would be nice?