Interesting game, nice graphics and color scheme, and somewhat fitting, but maybe not the most interesting music (but nice SFX).
Made it to the boss, but I was pretty much running away from the enemies the entire time getting there. I tried to fight through them several times but got literally nowhere.
Biggest flaw in this game is a fundamental flaw regarding making a top down shooter where the mouse is of use: The mouse should have an impact on aiming, preferably full 360 degree aiming (but I understand having made a game in this style in the past this makes animation more difficult for sure).
At least even having 4 directional shooting would be good where you could stay facing a direction, but you can't even do that in this game, so often you have to run towards enemies and take damage to even be able to hit them. If the shooting in the game (a shooter) is incredibly difficult to use, you need to scale the difficulty elsewhere to make it decent fun.
A 4 direction shooter game where enemies can shoot at you from angles other than your own available angles is just plain evil. It's sorta similar to giving a boss a healthbar that takes 15 minutes to take away, yet punishes the player brutally for a single mistake, IE non fun game design.
Other than that, the only fault I could find is the characters hitbox being really annoying. My advice working with this perspective is to make 2 hitboxes, one a square or circle around the characters feet for their movement (colliding with walls) hitbox, because realistically a characters upper body/head wouldn't prevent them from walking up to a wall. The second hitbox should approximate the players body for enemy shooting at/hitting them, but shouldn't impact their movement.
I hope some of this feedback is helpful. Don't think I am trying to say you didn't put effort into the game, I thought it was a really interesting concept, though with some flaws. Definitely looking forward to see what you do next though should you tackle the genre again.