i think the level design was great and the best part, and the harder but optional route of collecting coins/filling blocks was cool. a lot of levels clearly worked trying to make sure to use the ai in creative ways.
that said, this game has a major flaw which is not explaining things, such as how you can even press down on a skull platform to go under it (which took forever to find out and caused me to think a level was impossible for a while).
this issue is also there for how to kill the bosses, but i think the bosses are... honestly way too difficult to the point of not feeling like a challenge but just frustrating, if that makes sense? i really wanted to see the game to the end but i couldn't get past the second boss no matter what i tried. i thought that somehow blocks falling on it when it hits them could be the way, but it was nearly impossible to reproduce and it was way too easy to die to it due to the speed so i wound up struggling for 15 minutes before giving up. the bosses need adjustments or at least a more clear way to fight them because i also have no idea how i defeated the first boss at all, and the first boss stops movement completely if you run out of blocks to place which i think is a bug.
this is a bit of a harsh critique on the bosses, because they felt just too punishing. an easy mode to add hp could be a nice addition or some other way to help alleviate the struggle aside from a clearer explanation on what to do for each boss.
but, aside from my own pain with the boss, i had a fun time. again, level design was the strongest part to me. it kept me interested in what the next level would be like and some levels had some crazy weird puzzles and combinations with what order to try and get all coins and blocks filled. but if you ever update the game, it absolutely needs a clearer explanation on some mechanics and adjustments to the bosses. regardless, great job and good luck, it was a fun experience and i'd be happy to play again if it ever gets an update to adjust things!