I really really loved this game, it's a fun puzzle game, I really enjoy spatial reasoning puzzles.
My only personal critique is that it seemed a lot of the levels were designed in a way that the solution seemed obvious as soon as I saw it, a lot of the 'wrong solutions' seemed placed there on purpose to look 'wrong'. The level this stands out in is the level that has two boxes blocking the way right at the start, with a channel at the top of the level where two boxes would fit. It was pretty obvious the boxes didn't go in there because you'd not have been able to turn around after pushing them in there, so these channels seemed superfluous.
I loved the music and the animations are perfect for the simplicity of the sprites, you're tutorial levels teaching new mechanics were also very very welcome and showed me how certain objects would interact with each other without the risk of me getting it wrong or misunderstanding how those objects worked.