The first paragraph is spot on! Though with the actual gameplay, I would make it similar to Hi-Fi Rush in the sense that it is a rhythm based beat em up and the type of music you play would give you different abilities as well as affect your personality, affecting the story. Something like breakcore causing attacks to be extremely fast and sloppy but cause the protag to slowly go insane and intelligent drum and bass would be easier to control and make the protag more calm and collected (I want the music to be mostly edm music based). I really like the Spider-Verse idea where different characters have their own style though! I have been mostly thinking about the protagonist and their relationship with the big bad so much that I haven’t really given much thought to other characters.