This is my last Metroid II post, I promise. It’s spoileriffic, so most of it’s hidden behind a jump. Sorry.
Even in 1991, game developers wanted their games to be lasting experiences, things that their target audience would be playing ten, 20, even 40 hours after they were done. I finished Metroid II in a little over seven hours. I’m satisfied — seven hours is no small amount of time to be entertained by a black and gray Game Boy experience — but what if I wanted to get more out of it? What incentive do I have beyond the personal satisfaction of pure mastery of the game to try to get through it again?
Well, by this point, the answer to that question was simple, because it was answered by the original Metroid: offer an incentive for mastery by changing the ending.