Fuuuuuuuuucccccccckkkkkkk.
I beat the game last night but I'm trying to beat the real last boss. I got to it maybe twice. This time I got an item that skips levels except for the very last. I make it to the boss, one heart left, I'm kicking it's ass, it's down to 25% health and one random enemy throws a bomb and kills me instantly.
I admire that kind of difficulty, it reminds me of Contra: Hard Corps (most underrated Contra by far) and how brutally hard that game was but you kept playing it trying to get all the endings.