great concept on a bullet hell game! few things i would change to better fit the jam.
I think using one style of bullet would have been fine. Basic circle. I don't think it was necessary to scale the bullets to be bigger or smaller depending on what the object was doing. Just firing the bullets out would have looked fine enough. I think it takes away from the Gameboy aspectness of the game but overall still really well done!
Music had a good start and maybe making it a bit longer would have been nice.
if you use Gamemaker, Turn off Anti Aliasing to make it so your text wont be blurry :) otherwise you might want to look into this for future jams.