I looked at a stream on YouTube for 3 seconds and it does look like another rpgmaker game.

Tbh UnderTale had a ton of lore and stuff to be fantheorized over and over in a relatively modest package. What happened to the earlier fallen children, Sans' real past, Gaster--and some of it was a bit obscure (the nature of Chara and meta aspects) or hard to get to (like the megalovania fight) so I'm all for extending the canon a bit. One theme in UT as I read it was not letting the fannish obsessions distance yourself from the rest of the world which sort of seems like hard to square with a sequel, but I wanna check whether there's elaboration on that front.