Guidelines for a Good Deltarune Theory:

 This is meant as humor. Please don't take it too seriously. 

Don’t Kill, and Don’t be Killed: 

Don’t make ad-hominem attacks against other people in your theories, and generally be respectful and remember the human (‘s FEELINGS). 

The Value of Fun:  

Enjoy theorizing and don’t take yourself too seriously. Having fun can be better than being right. The real theory was the friend we made along the way.  

Even Green Pippins Has Limits: 

A theory without evidence is just a headcanon, but that’s not a bad thing. This DM believes in Rule of Cool. 

P(A∩B) ≤ P(A), Even if P(A|B) >> A : 

Aka: The probability of separate events A and B is at most the probability of A, even if B being true means A is significantly more likely to be true.

Having a bunch of theories that all rely on each other to be true is a few steps away from writing an AU—but again, AUs are fun! It’s more just a matter of reminding yourself that your AU/Theory is unlikely. 

Deltarune is not Marathon Infinity(1996): 

The theory should not disrupt understanding content on casual playthroughs. Some people want to play games they can understand without spending ten hours consuming theory content. 

Also we're gonna find the mysterious girl/woman in the hidden text this time. I promise. 

Deltarune is not Undertale(201X), But… :

 You can guess at Undertale rules applying, but they might not, as seen with the lack of magic for monsters in the light world. Ideally a theory should not rest only on evidence from Undertale, but things in Undertale and the Alarm Clock Game are fair game for theorizing.

Deltarune might Be Omori: 

Comparing Deltarune to other possibly similar games like Omori or Oneshot is fair game.

You Know What Happens When You Assume!: 

Building off the last point, many of the comparisons made between Omori rely on Kris having been responsible or witness to Dess’ disappearance. This is not necessarily the case, but it is frequently taken to be canon. People often make good analyses that are taken as the be-all and end all on a subject, such as Misty Sparkles’ Gaster info Series, Andrew Cunningham’s narration and music analyses, Roots theory, the original NarraChara Undertale theory, and potentially Dess Knight. However, theories that were assumed to be true by a good portion of the fanbase between 2021 and 2024 have also been jossed or made irrelevant: consider Chess Theory and Tea Theory. It’s fine to use a commonly accepted theory as the basis for your theory, as long as you know there's a slim chance it might be wrong, but it’s also fine to issue a rebuttal.

A Good Soul Never Dies: 

Even jossed theories can be revived. See Kris Knight (by virtue of Kris’s soul being in Dess’s body), Chess theory, and Woody theory.

A Royal Scientist Did It: 

You may have at most one case of “Gaster Handwave” or “This is a Gaster Conspiracy” per theory, and try to avoid it if possible.

Always Bet on 1225: 

See above but applied to Dess. Try to limit Dess ex machinas.

Creator Shoutout: 

Deltarune is made by Toby Fox (writer/composer) Temmie Chang (main artist/animator), Robert Sephazon (producer), Gigidigi (concept artist), Kanotynes (Ch1 character concepts), Nelnal (character designer), Splendidland (artist and character designer), Chess (sprite artist), Everdraed (artist/video editor), PIXELATEDCROWN (Ch2 cutscenes and Tenna assets), Audrey Wayner (Tenna typography), Smallbu Animation (animation including the TITAN CUTSCENE), Clairvoire (pixel art assistance), and Kenju (Ch2 tile artist). Deltarune is NOT a one-person team, and most of the developers have projects outside of Deltarune they are working on. For example, Gigidigi is making a VN called Souls of Sovereignty, and Temmie Chang has previously made two games: Dweller’s Empty Path and Escaped Chasm. Deltarune is Toby’s original idea and he is the writer, but he did not make it alone, so while you may mention his writing decisions, you shouldn’t attribute the game solely to him.

You do Not Know Dogs (or Tems) on the Internet:

 You most likely don’t personally know the gamedevs, and while you might be able to recognize their distinct art/writing/coding styles, you can’t see inside their mind. “Given Undertale, I don’t think Toby would write like X” is fair game, but again, remember the humans and don’t be creepy and parasocial.