Wonderful pixel art, very atmospheric & immersive intro, and overall pretty fun combat!
If there was a bit more variation / powerups as the Player Character it may help deal with some of the later boss combat (ie. the laser and grab moves) but also I could get better at the game as they're clearly telegraphed!
I think the only thing I'd for sure add would be a screen shake, hit flash, or something like that to let you know your player character had been hit with an attack! I had a few times where I hadn't noticed my health had gone down because I was focusing on the bullet hell :)
Overall, wonderful pixel art, great hook / intro cinematic, and stellar work given the timeframe!