Aqfaq - I'll also add a note I made that I didn't put into my submission text:
"some shots may look like stray shots. without them being fired, the boss doesn't actually flash when it's struck by the shot in front. whether the shots register or not i don't know, but it doesn't waste any time to fire them anyway."
I didn't know the memory address for the boss HP, so thank you for pointing that out. And I know the input lasts longer than it should, but that's his happy dance! (though I suppose it could be easily edited out)
Cardboard - a couple of your points are addressed at 5:11 and 6:29 in the submission notes. And I don't know if it's the same game or not, I'm not familiar with that version
Thanks for the comments. I'm not sure I'll give it another go myself for a while, but please feel free to beat this time. It's a great game and people should be able to enjoy it.