I must say the game has a lot of potential, I love the Undertale-esque Boss fights were you dodge bullet-hell style. A few things that could make the game even better tough are first of all the collisions of the tile set which don't really work with the perspective of the game, you can't walk to the ledge of the island but just close enough so that your head is more or less to the border, which doesn't seem like a problem at the start but when you then get narrow passage ways with only more or less a few pixels of wiggle room you get to enter results in a experience which is pretty immersion breaking.
Also I personally would love to see a Volume Slider for the sound, because sometimes the music was nearly silent and that's pretty sad especially when there is such amazing music to jam too.
I would also personally think that instead of a "normal" difficulty of easy normal and hard at the beginning of the game it would be a lot more interesting if you could instead toggle (your own movement speed, health, enemy projectile movement speed) similar to how Celeste does it in the Assist Mode, which makes it possible for less talented players to enjoy the game nevertheless.
Now to the good stuff, first of all I love that you can interact with a lot of stuff in the world (drawer, bookshelf etc.) and will get different dialogue or dialogue that explains something more than just what you can immediately discern if you aren't blind.
Also the music is amazing especially some of the boss themes really help elevate the game to a whole other level. Then the fights themselves are really well made as well, especially learning the enemy patterns as they are always the same (more or less) can be pretty rewarding. Perhaps tough showing your current health and perhaps even a certain indicator when something will come from the side could be nice as it would feel less bad if you are just currently on the right side of the board and can't react in time.
Besides that tough amazing game and I can't wait for how far it will come :D.