Ok, so a while ago, one of my irl friends was talking about Undertale with me, and he said, ”when you’re in Snowdin, sans gives you the word search ”puzzle” but the restaurant that made the puzzle isn’t in Undertale, it’s in Deltarune. So HOW did Sans go to that restaurant to get that.” Well, I’ve finally figured it out. If you go to Sans and Papyrus’s house in Snowdin, Sans’s room’s door has flames burning under it, in Deltarune, you can use doors that have flames burning under them to travel around. So, Sans got to that restaurant through his door, which leads into Deltarune. It’s a theory. Very valid theory.
Toby Fox owns Undertale and Deltarune