Deltarune Observations, Theories, and Speculation

WARNING: These pages will contain spoilers for the latest update of Deltarune, as well as any side-content such as newsletters, ARGs, and things like the Spamton Sweepstakes. As of the time of writing, this includes:

• Chapters 1 to 4 of the game, both the English and Japanese versions (which only have minor differences with a few exceptions).
• The Spamton Sweepstakes.
• Everything we know about on the Deltarune website as of June 2025.
• All newsletters as of the chapter 3 / 4 release newsletter.

Consider this the one and only spoiler warning on the site, as otherwise I'd have to constantly give warnings and blank out most of each page. Furthermore, many screenshots will be in Japanese since I took more on my Japanese playthrough than previous ones. Eventually I'll get around to adding translations in some way, especially when the Japanese has important differences from the English that impact speculation and theorycrafting.

I have tried to verify everything myself, but for some things I don't have access to (mainly PS4/PS5 trophies), I had to rely on the Wiki and videos/images for evidence. Pages with no link listed below are planned but not ready yet.

• (READ THIS FIRST) Themes of Deltarune. Not themes in the musical sense, but the metanarrative and what I think Toby's intent is. Very incomplete at the moment.
• W.D. Gaster and the nature of the Dark Worlds.
• The Eggs and the Man behind a tree.
• Differences between the English and Japanese versions. Covers Chapter 1 only so far.
• A list of crack theories I find interesting or funny but don't necessarily believe in.

I'm also putting my conclusions from the above together into a grand-unified theory that tries to explain as much as possible with what we've been shown in chapters 1-4.

Some useful links to information on Deltarune:

• Deltarune - the official website. Has hidden pages that relate to the game story.
• Undertale / Deltarune Newsletter Archive - Updates on game development and previews of new chapters.
• Deltarune Wiki - the main English-language wiki. Good for summaries, basic information and graphics.
• Deltarune Text Dump - all the game text from Chapters 1-4. Good when you want a specific quote. Has some basic functionality for filtering by chapter, but doesn't show speaker names for dialogue.