I stayed up all night playing this game, it's that good! Also, is there by any chance a playlist for the music used?
Nice!! On the music, uhh, I don't know if I can do that, some of it I commissioned for the game but a lot of it is free-use content from various sites/artists, some of which might have rules against that. The About page links to the sources for most music, if there's a particular one you're looking for I can try to help too!
Additionally, in most fantasy settings there is aura for the physical type users and mana for magic type. Disregard this if you're not planning on introducing aura, but if you are planning on introducing aura, maybe the nature of the aura can be tainted by aether, nether, or abyssal forming new types of abilities that primarily do the damage type of the corresponding corruption.