I have been replaying both Undertale and Deltarune side by side in 2026, not just because they are two of my favorite games, but because I keep noticing strange echoes between them. What starts as a nostalgic replay quickly becomes an obsessive hunt for clues. If you have not played either game yet, consider this your spoiler warning: I am about to dig into some of the biggest connections that link Toby Fox's two worlds.

Even before you press start, the first connection is hiding in plain sight. Deltarune is an anagram of Undertale. That alone feels like a wink from Toby Fox, but once you combine it with everything else, that simple word scramble stops feeling accidental.

One of the creepiest discoveries happens when I walk south of town in Deltarune. In the graveyard, there are three large gravestones. If you look closely, their names match the amalgamates from Undertale, those tragic monsters Alphys tried to resurrect with human souls. In Undertale they are still barely alive but corrupted. In Deltarune, they seem to have been laid to rest naturally. Does that mean Deltarune is a timeline where Alphys never performed those experiments?

Then there is Clam Girl. In Undertale, if you talk to her on a non-genocide route, she mentions her neighbor's daughter named 'Suzy' in yellow text, which usually signals something important. At the time, it felt like a dangling thread. Now in Deltarune, we meet Susie, Kris's tough but lovable classmate. Same name, different spelling, and suddenly that old Undertale dialogue feels like a prophecy.

The romantic side of both games keeps me warm. Undyne and Alphys return in Deltarune with their personalities intact. Their relationship is more subdued at first, but by the end of Chapter Two, I am delivering heart-shaped candy from Undyne to Alphys. It is adorable. Yet I cannot ignore one visual difference: Undyne has both eyes visible in Deltarune, while in Undertale one eye is covered. Could Deltarune be showing an earlier version of her? Or is this simply a different version of the same person?

Kris's family also mirrors Frisk's in ways that are too specific to ignore. Toriel is still the nurturing mother who adopts a human child and bakes pie. Asgore is still warm but flawed, and he has been fired from the town police after some incident that Kris refuses to discuss. In Undertale, Frisk's family is broken by tragedy; in Deltarune, the tragedy is quieter but still present. I keep asking myself whether these are the same people living different lives or completely different people sharing familiar roles.

The multiple universe idea is practically baked into Undertale. The game itself talks about other save files and alternate timelines, and Flowey invokes that meta-awareness directly. A multiverse would explain why so many characters and themes overlap without requiring Deltarune to be a simple sequel or prequel. Maybe every playthrough, every route, and every reality exists side by side.

And how could I skip Sans? He shows up in Deltarune working at a local shop, still lazy, still sassy, and still hinting that Papyrus is out there somewhere. The detail that truly rattles me is those warp doors used for fast travel. They look very much like the door in Sans's bedroom in Undertale. Is Sans able to move between these realities? The doors alone make me think yes.

Finally, there is W. D. Gaster. He may be the most unsettling piece of this puzzle. In Undertale, Gaster is a scientist erased from existence, with only remnants left behind. In Deltarune, calling on the cell phone in the Dark World plays that eerie Gaster theme. The same motif appears at the bunker in town. Why is his music following us? What does he want?

So after all this, where do I land in 2026? I still do not have a clean answer. The anagram, the graves, the shared names, the doors, and Gaster's music all suggest Deltarune is neither a strict sequel nor a simple prequel. It might be a parallel world, a shifted timeline, or one save file among many. That uncertainty is exactly why I keep returning. What do I think the next chapters will reveal? If Toby Fox's history is any hint, the answer is probably already hidden in plain sight, waiting for someone to notice.