The massive Nintendo leak that happened over this last weekend, often referred to as the "gigaleak," is still being picked through and dissected. It included old versions of many classic Nintendo games, including prototypes and cut concepts. A number that have surfaced recently show just how different the Nintendo 64 Zelda games could have been.
This gigaleak is part of a much broader leak of Nintendo info that has taken place this year, though this last weekend's was pretty significant in size. It ranged from unused sprites to full-on characters, like Luigi in Super Mario 64.
On the Zelda end of things, we get a glimpse at a few ideas of where the Master Quest could have gone. Twitter user @AeroArtwork compiled a thread of findings as people discovered them, which seem to include unused maps like one for Ganon's castle, where it could have acted as a hub of sorts.
As shown by Psi-Hate, there was also a boss rush-style dungeon uncovered in Ocarina of Time code, with a number of micro-dungeons culminating in boss rooms. Honestly, a Legend of Zelda boss rush sounds pretty cool. It's important to note here that these are all just concepts—what stage of development they made it to is not readily apparent, and the DD notation on these files led the discoverer to believe they might have been tests for the Nintendo 64DD.
For Majora's Mask, one famous quote from a beloved Nintendo vet was confirmed. In an Iwata Asks column, former Nintendo president Satoru Iwata asked Zelda producer Eiji Aonuma about the original day and time system behind The Legend of Zelda: Majora's Mask. Aonuma says that "at first, it was one week." This would eventually become three days that looped, as Link tried to Groundhog Day his way to saving Termina. There was also an unused archery minigame in Great Bay discovered.
The discovery of some text in the gigaleak backs this idea up. It was already known and confirmed by Nintendo, but still fascinating to see actual proof of it.