Deltarune features many returning characters from Undertale, but unlike most, Sans exhibits some unique abilities and knowledge of timelines.

The result sounds pretty authentic, evoking fond memories of all of the interesting and helpful comments Sans would pepper your journeys with through Undertale's labyrinthine Underworld.

There is a browser based simulator that gives players the chance to relive the notoriously difficult Sans fight from Undertale.

Omega's standard entrance video was interrupted with a dialogue scene in the style of Undertale - with custom graphics and authentic talking noises - where Sans offers to tag in.

Sans, a major character in the cult indie game Undertale, will appear as a playable character in Pop'n Music.