Bro, this is a sick game base! This has a ton of potential -- I was hooked doing the whole dodge gamut, tossing the trident and running around like a madman trying to kill the squeebs as quickly as possible. Letting too many enemies spawn on screen turns the game into a crazy bullet hell, so that was fun to adapt to! I also really enjoy the pixel art aesthetic and the animations, as well as the bullet-timey hits that felt impactful and reactive to how I was doing.
I didn't know there was a mirror mode until I died the first time, and then once I figured out how to switch (dash into mirror? something like that), I stayed in that mode because there I could recover health from some of the enemies I killed, which let me last way longer! Not sure if that mode is supposed to be timed so you could recover some health, but that really piqued my interest and I enjoyed the theme take. I would've loved to see an extra UI indicator beyond health bars, like the current run time, just so I had extra sensory input from the game as to the current run.
Very curious to see if/how you would develop this further! I could totally imagine more levels, more enemy types, Binding of Isaac or Vampire Survivors-style pickups, and so on.