Nintendo Stopped Super Metroid From Being Unlockable In Metroid Prime - IGN - IGN

A Super Nintendo classic was almost playable within Metroid Prime on Nintendo GameCube, until Nintendo stepped in and stopped it from happening.

In the latest episode of the Kiwi Talkz podcast, Metroid Prime developer David "Zoid" Kirsch shared insight into the development of Prime, including this retro easter egg.

Zoid said he first played Super Metroid after he was assigned to work on development of Metroid Prime, but he completed the game twice in under a week because he loved it so much.