A friend of mine explained that there are overlapping phobias of water and deep dark spaces that this game triggers; he said it's unbearable to play the later levels.

I'd imagine anyone with claustrophobia would struggle with the last couple levels as well since they're essentially a battle against the screen crushing you.

I just checked what the final boss looks like, combined with the phobias... glad I didn't finish the game as a kid.

Thanks for the article, great read!