It appears The Legend of Zelda: Breath of the Wild uses an upgraded version of Nintendo’s classic Mii character creator to design many of its NPCs.
That’s according to datamined research from HEYimHeroic, a self-professed “Mii expert” who runs the Wii Facts Plus blog.
Within Breath of the Wild’s files, NPCs are referred to as “UMii”s (Ultimate Miis?), who use a combination of familiar Mii facial components for their various designs.
Breath of the Wild’s versions of these components are more detailed, and stylised to fit the game’s art style. But it is noticeable how many NPC characters share various bits and pieces of the same face parts.
This also means that, with a bit of code injection, it is possible to customise the game’s UMii characters to display with different face pieces, and even get your own Mii in Breath of the Wild too, as HEYimHeroic shows: