Not to be confused with the video game Deltarune, the delta rune is a recurring symbol throughout the video game Undertale. It consists of two wing shapes mirrored across a circle, with three triangles underneath, two of which are facing up and one down, with the one facing down being slightly lower than the other two.

It is located in many points across the game, including in the introductory screen, on the character Toriel’s dress, and on multiple doors and windows.

The name is an anagram of Undertale, as is the name of the game Deltarune.