D'ni Numerals (Myst)

D’ni numerals are the fictional numeric system of the D’ni civilisation in the Myst adventure-game franchise (Cyan Worlds, since 1993) and its sequel Riven (1997). The D’ni are a vanished underground civilisation that mastered the Art of writing worlds — the famous Linking Books that open portals to alternative Ages.

The system is base 25 (vigesimo-quintuple), a conceptual choice by brothers Rand and Robyn Miller consistent with the mathematical esotericism of the D’ni in fiction. The repertoire holds exactly 25 unique glyphs for digits 0 through 24, and larger numbers are composed by positional juxtaposition — like our base-10 Arabic numerals, but with 25 “atoms” instead of 10.

How does the numeration work?

CipherChronicle treats a run of decimal digits as a single integer that is converted to base 25. The result is a sequence of “D’ni digits” (each between 0 and 24), most-significant first, each rendered by its own glyph. The technique echoes historical base-60 (Babylonian) and base-20 (Maya) numerations.

Examples: 25 → [1, 0] (one D’ni-1 followed by one D’ni-0); 624 → [24, 24] (two D’ni-24 side by side); 625 → [1, 0, 0] (three glyphs). The current year 2026 is written [3, 6, 1] because 3·625 + 6·25 + 1 = 1875 + 150 + 1 = 2026.

Cryptographic strength: none. It’s a notation, not a secret cipher — digit-frequency analysis would reconstruct the table in a few pages of text. The interest is cultural for fans of Myst / Riven / Uru, a founding series for narrative adventure games (50 million copies sold worldwide).

Historical and modern usage

• Myst, Riven, Uru games — appears in in-game D’ni inscriptions.
• Myst community — fan art, riddles, Mysterium conventions.
• Playful pedagogy — example of fictional base-25 numeration.
• Official Cyan — D’ni encyclopedias and booklets.

Related variants

• Cistercian numerals — see our entry, European graphic base-10000 numeration.
• Babylonian numerals — see our entry, Mesopotamian base-60 numeration.
• Kaktovik — see our entry, Iñupiaq base-20 numeration.

What are the weaknesses?

• Numbers only — alphabetic text not supported.
• Public numeration — table documented in Myst Wiki and dCode.
• Readable by analysis — digit frequency quickly reveals the base.

The 26 glyphs (0-24 + special “25”)

D’ni quirk: decimal 25 (the base itself) is not written [1, 0] but has its own atomic glyph — the “cornerstone” of D’ni numeration in Myst lore. From 26 onwards, standard positional composition resumes ([1, 1], [1, 2], …).

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

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24

25