As you might remember during one of the two newsletters Toby Fox has sent out sometime after the release of Chapters 3 & 4, he said this: “I don’t think that the game will be released in the first half of 2026.“ (Fox, Toby, Undertale/Deltarune Newsletter Fall 2025, Paragraph or line 66, sentence 3).
If you do the calculations, half of a year is 6 months right? So some point likely after June or maybe during June, the window will start for the release date, right? Well, it’s not actually that simple. As you know, Deltarune Chapter 1 released earliest 7 years ago on October 31st, 2018 (Link here: https://deltarune.wiki/w/Chapter_1 ). Deltarune Chapter 2 released earliest 4 years ago on September 17, 2021 (Link here: https://deltarune.wiki/w/Chapter_2 ). And finally, Deltarune Chapters 3 & 4 both simultaneously released earliest on June 4, 2025 (Link here: https://deltarune.wiki/w/Chapter_4 ). Now you might be asking, “What does this have to do with anything,” and you’ll be surprised. Now, let me reverse that question onto you. Or rather, rephrase it. What does those dates all have in common?
…
Yep, you’re right, they all released during warm seasons! So, if we were to apply that pattern to Chapter 5 (and its release limit of after or during June), we get the following months: June, July, August, September, and October. Any months later than that are still a possibility but still highly unlikely (at least from my perspective). This means that for people in Middle School, High School, or College/University, that means there is a very, and I mean VERY, VERY narrow window where Chapter 5 might release during your summer break, however this is really unlikely, because as of now, “translation of Chapter 5 next week! Meanwhile, we've been polishing the game and doing some preliminary internal bugtesting on PC. Heavy bugtesting across every console will happen when the Japanese translation is done.” (Fox, Toby, Bluesky, February 10, 2026). However, this is a progress report that is almost a month old (technically it is but it hasn’t been 31 days yet, and I consider that a month), so maybe they are getting closer and we don’t know it yet (we don’t have to, it’s their game).
What further proves this is the fact that the season the games take place in seems to be Fall, as the trees are yellowish-orange (like candy corn orange), and we all know what happens to leaves during Fall.
However, this was just for fun and something to do while we wait for the actual release date announcement. If any of you have any other valid points of opposition or agreements, feel free to let me know your opinion!
Like I said, this wasn’t made out of impatience, don’t take my little theory to heart, it is still unlikely that I’m incorrect. Truth in all, Toby does what he does and we get it when we get it, so if he decides for it to be released on December 25 (shocked gasp), by all means he can do it. We don’t control the design process. Toby and his team does. (Well, Toby isn’t the producer, exactly, but like… c’mon.)
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I don’t really know where to put this, so as of this edit (March 10, 2026) I will have put it into the Deltarune Discussion Category.