oight, I can rate this properly and fully now that I've managed to beat the game.
-there are two conflicting music tracks playing at once during the entire game. I had to mute the audio because I couldn't stand it anymore. the individual music tracks are fine, but playing two desynced tracks at once gives very unpleasant results
-there's invisible coal hidden inside the crane box, which feels scummy
-something is not quite right with the coal/soda/spinch UI readouts, but I can't tell you how to fix it because I don't know what the correct readout is supposed to be
-sapphy drops straight down like a rock after punching in midair, at a speed that feels unnatural
-it's possible to jump to the roof of the crane box from the bottom without using the elevator, and the window is so tight that I suspect this is not intentional
-sapphy can go out of bounds above the top of the first map and the camera can't reach her there
-gaye can be seen floating in midair in the first map on the right side, and despite an X interface popping up if you jump towards her, is not interactable
-there should be some indication that you're supposed to return to your boat after collecting all the required coal. I wasted too much time wandering around and testing every possible interaction before i managed to progress
-the gag where a hint sign is revealed after doing the thing you needed the hint for is funny at first, but there's a reason why designers don't do this
-on a related note, the player would probably figure out the solution to these roadblocks naturally if you just added more things to punch (like destructible barrels) so they remember they can punch. it's easier to forget when you're not punching anything at all for 80% of the gameplay
-bone throwing skeletons throw slightly too fast. if it's even possible to reach them without getting smacked by a bone, the window is way too tight
-sapphy is just slightly too tall to reach a spinch in the underwater soda collecting section. I suspect this is unintentional because I didn't see a sign mocking her for not being able to reach it. you could fix it, but i think it would be funnier to add the sign
-the underwater overlay is too opaque and makes it difficult to see
-the speed at which mouse scrolling zooms the camera should be reduced somewhat, for the benefit of trackpad users