DeltaRune Part 3 - 9/11 Was An Inside Job?
DeltaRune isn't exactly a sequel of Undertale, though both games are made by Toby Fox. I guess the simplest way to put it, this game takes place maybe a few years later along the timeline from Undertale, but in like an alternate/parallel universe? In this world, it seems the War of Monsters and Humans never happened, and Monsters live above ground, and there don't seem to be any humans anywhere. Perhaps the humans are trapped underground somewhere? Who knows!!
Anyway this is a cool ass game. Enjoy