Eye Sigil ARG/Mini Metro
Mini metro is a game developed by Dinosaur Polo Club, available on Steam, GOG and iOS store. It was fully released 06 Nov 2015, but was available in early access long before that.
The sigil was added in an update on 13 Feb 2015 (the game was still in Early Access).
Sigil appears by going back and forth between credits and menu.
The player has to solve the Canberra level by recreating the sigil.