The art is really nicely done. I like the pixel art overall and the spreading effects. Although I'm not exactly sure why the grid was necessary, maybe to help with navigation? I think with all the ship movement it's clear enough. I mentioned because it seems to clash with the pixel arts a bit.
The audio is also nicely done, although it could used some pitch shifting probably to reduce audio fatigue.
The theme fits very well. The itch page looks great, although because the default "Play Game" button on itch is kinda small so it may not look immediately clear on your page, but I think it's a minor thing.
I tried the big ship first because I saw that it was the ship featured on the game page, and I was about to mention that the game feels slow because the big ship fire rate is slow. But then I tried the small ship and with the much higher rate of fire it feels much funner.
I have mixed thoughts on the control scheme. I played on the keyboard. When I started the game and when the game is in its early stage, I think it makes much more sense for the movement of forward (on keyboard it's the W key) to be tied to the direction of the ship's head, and not the XY axis of the 2D space. I repeatedly kept trying to press W to make my ship goes into the direction that I was firing the bullet in, only to be moved up in the 2D space, even after some time playing. However, I can see how after a bit and you have accumulated some parts and the bullet starts flying in all direction, it could make more sense to be the way it is now. That and perhaps as a twin stick shooter game meant to be played with a controller it's better. With all that being said, as it is a web game on itch, I think you should always prioritize the mouse and keyboard control scheme since that's what most players will use. I also think having all the buttons bound to the left hand side is not a good choice because my hand gets really tired really quickly having to keep pressing many buttons buttons repeatedly.
One thing that I didn't like however is the fact that the shooting is bound to a key or mouse and you have to press or hold the key down to keep shooting. I don't see why I would ever want to not shoot the bullets so why not just make it fully automatic?
Overall I think it's a nice game, but I would change the control scheme a lot for it to be really fun.