We've covered it extensively here on Nintendo Life in the past, and during a search for more information about it YouTube channel DidYouKnowGaming? has actually uncovered another Zelda spin-off Retro pitched to Nintendo. It was known as Heroes of Hyrule.
This game - styled like Final Fantasy Tactics and sounding a bit like Breath of the Wild - would have focused on three heroes (a Goron, Zora and Rito), who lived 100 years in the past and set out to rescue Link. Time passes and Link would then be "an old man" who ran an antiquities shop.
The source featured some concept artwork alongside this surprise in its latest video and intends to share more details about this project in a future upload. When we learn more, we'll let you know.