The Eternity II puzzle
Eternity II is an edge-matching puzzle: 256 square pieces on a 16×16 board. Wherever two pieces touch, their half-patterns must form the same motif; the board rim must be grey. That's the whole rule. It fits on a coffee table, and it has resisted every human and machine attempt since 2007.
A two-million-dollar grudge match
Christopher Monckton releases a 209-piece tiling puzzle with a £1,000,000 prize, convinced it will stand for years.
Cambridge mathematicians Alex Selby and Oliver Riordan claim the million. They didn't out-search everyone; they out-thought the puzzle, proving it had far more solutions than intended and steering their computers to the easy ones.
For the sequel, Monckton brings in the very people who beat him. Selby and Riordan computer-test candidate designs so the new puzzle resists every trick that killed Eternity I: a designed solution, balanced color counts, and no exploitable statistical structure.
256 pieces, 22 edge motifs, published by Tomy. Prize: $2,000,000 for the first complete solution. Four companion 'clue puzzles' each revealed a hint placement.
At the first prize scrutiny, Louis Verhaard's team from Lund, Sweden holds the best partial solution, 467 matched edges out of 480, and wins the $10,000 consolation prize.
Nobody ever submits a complete solution. The $2,000,000 is never paid out. The puzzle quietly goes out of print, and becomes a legend.
Hobbyists with modern hardware push the record to 468, then 469 (Joshua Blackwood & Peter McGavin, 2020), then 470 (Blackwood, 2021) on the official puzzle. That 470 has stood ever since — tied once (Jef Bucas, December 2024), never beaten: ten edges still separate humanity from 480.
Anatomy of the piece set
A full board has 480 interior edges to match (2·16·16 − 16 − 16). "Score 467" means 467 of those 480 edges match. No two pieces of the set are identical, and none is rotationally symmetric: the designers made sure every piece is genuinely distinct.
The 22 motifs (and one grey)
A piece is four triangular motifs (up, right, down, left) meeting at the center (here: the famous center-clue piece, n°139). A motif is therefore always a half-pattern: the full design only appears when two pieces meet and their triangles complete each other. That's what "matching an edge" means.
Every edge carries one of 22 motifs, plus grey for the outside rim. The distribution is no accident: count them and you find a designed signature: five rare motifs appear only 24 times each and only on the frame (border-to-border joints); five appear 48 times; the remaining twelve appear 50 times. Every count is even, because every edge of the hidden solution is a matched pair. In community notation each motif has a letter (the URL format of e2.bucas.name).
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All 256 pieces
The full official set, by piece number (1–256), shown in their stored orientation (rotation 0°). You can also lay them out on a board in the Board Viewer.
The five official clues
The rules sheet pins one piece, piece 139 at square I8, and Tomy sold four smaller "clue puzzles" (two in 2007, two in 2008) that each revealed another placement. A board that respects all five is called strict-canonical; most record boards only respect the mandatory center clue, which is why the best board with all five clues (464, Benjamin Riotte, 2026) trails the open canonical record (470).
The pieces below are shown as placed on the board, already turned to their clue rotation (printed under each piece). At 0° a piece sits exactly as in the official piece list.
Best known boards
| Score | Who | Notes | |
|---|---|---|---|
| 470 / 480 | Joshua Blackwood, 2021 | the canonical record — tied once (Jef Bucas, December 2024), never beaten | view |
| 469 / 480 | Blackwood & McGavin, 2020 | the previous record — long quoted as the ceiling | view |
| 468 / 480 | Joshua Blackwood | view | |
| 467 / 480 | Louis Verhaard's team, 2008 | won the $10,000 partial prize | view |
| 464 / 480 | Benjamin Riotte, 2026 | best strict-canonical board (all 5 clues respected) — beat Gauthier's 460 of 2023 | view |
Why brute force is hopeless
Formally, edge-matching puzzles are NP-complete (Demaine & Demaine, 2007); they belong to the family of problems for which no efficient general algorithm is known. Eternity II is widely considered one of the hardest instances ever put in a box. The known clever methods that broke Eternity I were specifically engineered out: see Research. Wondering whether it is even solvable, or a scam? See Is it a scam? Can it be solved?
Common questions
- What is the Eternity II puzzle?
- Eternity II is an edge-matching puzzle released in 2007: 256 square tiles must fill a 16×16 board so that every shared edge shows the same colored pattern, with the border edges grey. It carried a $2,000,000 prize for the first full solution.
- How many pieces does Eternity II have?
- 256 square pieces, each with a colored half-motif on all four edges, drawn from 22 different colors/motifs. They fill a 16×16 grid — 480 internal edges that must all match.
- Why is Eternity II so hard?
- The number of ways to arrange the pieces is about 1.115 × 10^557 — vastly more than the atoms in the observable universe. No algorithm can check them all, and the puzzle was deliberately designed to resist brute-force computer search.