Great game! I love the art and I had a really fun time playing this. Some of the levels took a couple tries to get right so I’d say the difficulty was just right - not too easy or too hard.
There are things to improve though. I didn’t really like the controls, especially jumping. You should try setting the gravity a lot higher so it doesn’t feel like the player’s on the moon. Physics were sometimes a bit inconsistent, especially when pushing boxes. Sometimes the box would roll around like it weighed nothing at all and sometimes it felt like I was pushing a boulder uphill.
I’m also not a big fan of the enemies. The way they move makes them very hard to hit, they take too many hits to kill and I don’t think they really add much to the game at all. Sometimes I would finally get the puzzle right only to randomly die to an enemy just before opening the last door which felt really annoying. I think it’d be better if the enemies weren’t in the game at all or if they at least moved more “along the grid” so they’d be easier to hit.
With a tiny bit more time, this could be a really great game. Good work!