I'm a big fan of rhythm games in general and I loved the ideas that this game explored quite a bit. Props to you for getting procedural generation and pathfinding in the game, those are not easy things to implement (and get right) given the time constraints.
For a game with an emphasis on the down-beat, you might want to pick/compose a song with more of an emphasis on the down-beat itself. Additionally, having some kind of rhythm indicator would help too (i.e. Crypt of the Necrodancer has the bar at the bottom indicating the beat, Rhythm Heaven mini-games mostly feature characters that bop to the beat of the music). These are all not simple tasks (making a bop/indicator that feels right, syncing the animation to the BPM, etc.), but it might've been more impactful to the game than the pathfinding or procedural generation.
I like the idea of "combo"-ing arrow key inputs to make a directional attack. It just didn't make sense to me at first (why do I need to make three arrow key inputs to attack to the left instead of just pressing left?) Maybe it might make sense for a weapon like a mage's staff where the combos end up casting some sort of spell or what not? Another option would be to require players to make arrow-key inputs to a specific rhythm (maybe on the upbeats?), and then introduce different weapons (like bows) that require a different rhythm/combo.
It's also pretty hard to make a 2D tile-based rhythm dungeon crawler without making it just like Crypt of the Necrodancer. Regardless, good job getting all of the stuff you got in for the jam, it's not easy to make rhythm games functional within the timeframe.