Uncovering Secrets in Zelda's Tears of the Kingdom.

The Legend of Zelda: Tears of the Kingdom has a massive secret involving the Depths, which is a literal dark mirror of the surface above, with all its major locations and landmarks corresponding to ones on the surface. The topography seems to mirror itself too, with tall mountains on the surface being deep valleys with mines in the Depths. Nintendo essentially created a "Dark World" version of Hyrule underground.