I love the heart art/animation/sound effect, well done.
Tutorial is good too. Intuitive, short, with a little bit of story telling sprinkled in.
I like the concept and i want to see where it goes, but i can't get far.
For me it's impossible to get far because if you get a nightmare or a gym you lose all your durability and you can't buy anything significant in shop to offset that, i didn't fail a single action, everything was closely on beat.
Maybe durability should decrease based on how closely you are to the target BPM?