Board Thread:General Discussion/@comment-36624593-20181205013841/@comment-28517148-20181206150023

@VideoCreepso3949 Toby Fox said that Deltarune is set in an alternate universe...

@Pino Vermelho Its an Alternate Universe (TOBY WORDS!!!)...

Sources please.

Here is Toby Fox's message where he explains Deltarune is not Undertale - http://www.twitlonger.com/show/n_1sqn3p9. Very straightforward, nothing about a Alternate Universes.