I like it how this game manages to fit so much - regular fights, boss fights, items, inventory, map,... - and all of that in a small package and without feeling overwhelming! :D
Some background music might be a nice addition, perhaps even to make boss fights feel more dramatic, but honestly, I never felt a need to hear it and sound effects sound pretty good. :)
Btw. I might had overdid it with almost paranoidally collecting extra HP, so that it overflowed the UI, lol: