Very cool! :D Thought, I'd give some friendly feedback, here are some things I noticed while playing:

The level-up reward is initially a bit overwhelming, I thought I somehow picked up some item at first and didn't really associate it with having killed enemies. I was also a bit overwhelmed at seeing all six options, having to pick from one of e.g. three random upgrades would be a lot less intimidating

The dash is also a little awkward to use, as it teleports you to your mouse, but that's where you're shooting, which is therefore usually filled with enemies. Having it dash in the direction you're moving would be a bit more intuitive :)

Also, I didn't want to go very close to the first boss, I thought the spinning rectangles were hitboxes, and I didn't really get a good look at it D: 
You can fix this by having the camera lean a bit more to wherever the mouse is pointing, so that way, I can see what I'm shooting at :D

Love the effects and juice, as well as the atmosphere  :D