Fun game! It works very smoothly and I wanted to keep playing to get farther (looks like I max out a bit after two full plays of the song). The visuals are very faithful to the inspiration, and you did a great job imagining and bringing to life gameplay around the original images -- the character-switching and heart-rebuilding mechanisms were clever and well done. You also balanced the difficulty well, the UI is great, and night mode was a nice touch. My only bit of feedback is that after firing a heart, the player "sticks" and can't move vertically until the heart animation is complete (perhaps because the player and heart-shot are one animation, or maybe parent-child?). My instinct was that the player should be able to move once the shot is fired, fwiw, but maybe this was meant as a downside to using the heart. Nice work!
Thank you for the review, I'm happy that you liked it!
The movement restriction during the attack was intentional as an aspiration to resemble how it goes like in the original concept, but also works as an added layer of difficulty like you said. But I can see it might feel a bit janky and could abide some smoothing, I'll consider revisiting it!