The characters are good, the music is calming and somehow fitting, the mechanics are easy to understand, but the recall makes it too easy, you can always recall and you get full life and you can grind the first level to unlock all the new stuff. maybe recalling could cost money if its in a room full of enemies. or maybe not restarting the enemies once you cleared the room.
also, having to battle against mechanic and organic enemies is a good idea, but the organic enemies should give something, maybe a new "coin" to unlock even more stuff, like, a way to cure the heart.
over all, its agood game, from the idea, mechanics, the music and the visuals, but it need polishing.