I like the concept and artstyle !
The characters are very expressive and well animated, the music fits the mood as well.
Gameplay wise i had trouble with the cooldown mechanic i wasn't sure if i was actually slowing the heartbeat or not cause on the first screen it stayed at 220
Also small technical issue, but when playing i noticed you let the debug console and it sometimes mentions you've got a Raycast2D node missing just so you know.
Other than that i like the ideas on display here and like i said the pixel art is pretty good :)