Every so often a BOINC project turns up that is pure, stubborn, beautiful mathematics — no cure to find, no galaxy to map, just a problem that has refused to fall for nearly twenty years. Eternity II is that kind of project, and it is now open to volunteers.
📖 Full write-up on the BOINC Synergy wiki: boincsynergy.ca/wiki/Eternity_II
The puzzle that kept the money
The physical Eternity II puzzle launched on 28 July 2007, devised by Christopher Monckton and sold by TOMY UK as the sequel to the original Eternity puzzle. It came with a US$2 million prize for the first complete solution. The competition deadline passed at noon on 31 December 2010 and the money went unclaimed.
The format is deceptively simple. There are 256 distinct square pieces that must be rotated and placed into a 16×16 grid so that every pair of touching edges carries the same pattern. Four corner pieces have two grey sides, 56 border pieces have one grey side, and the remaining 196 interior pieces have four coloured sides. Grey edges must face outward. There are 22 non-grey edge patterns in play, and a finished board contains 480 internal adjacencies — so a perfect board scores 480 out of 480.
Nobody has ever publicly produced one. The best result recognised during the prize competition was 467 matching edges, found by Louis Verhaard of Lund, Sweden, who collected US$10,000 for it after the 2008 scrutiny date. In August 2020 Joshua Blackwood posted a board with 468 matches to Reddit — a community report rather than a verified complete solution. That is where the state of the art sits: twelve edges short, and stuck there for years.
Why it is so hard
Ignore the border rules, the clue piece and the colour matching for a moment, and 256 distinct pieces can be permuted and independently rotated in roughly 1.15 × 10661 ways. Account properly for the four corners, 56 border pieces, 195 unfixed interior pieces and the mandatory central hint and you get a tighter upper bound of about 1.12 × 10557.
Those are upper bounds, not a forecast of how much work the project actually has to do — edge colours, fixed clues and good pruning heuristics throw away enormous regions of that space without ever examining a complete board. But they explain why this is a textbook target for distributed computing. The search splits cleanly into independent chunks, and independent chunks are exactly what BOINC is for.
What the project actually does
Eternity II coordinates a distributed search for improved arrangements of the board. The server hands each host a small, independent slice of the search space. A CPU solver examines candidate boards, prunes branches that cannot usefully continue, and returns its output. The server validates what comes back and keeps strong boards for the community's ongoing search.
The project is explicit that every additional matching edge counts as progress. This is a search for a better score, not an announcement that the puzzle has been cracked.
Who is behind it
The solver is the work of Benjamin, who was already running it as a stand-alone application before taking it to BOINC. He asked for help in the BOINC Discord community with running the stand-alone instance alongside a BOINC deployment, and the website and server were subsequently set up with assistance from rebirther, the long-time administrator of SRBase. Benjamin administers the project day to day.
What you need to run it
- Application: Eternity II CPU solver (pilot)
- Windows x86-64: version 2.29
- Linux x86-64: version 2.26
- GPU: none listed as of 30 September 2026
- macOS: no native solver listed as of 30 September 2026
The project invites participants to install BOINC on Windows, Linux or macOS, but whether your host actually receives work depends on the application versions available for your platform. Right now that means 64-bit Windows and 64-bit Linux boxes are the ones that will stay busy.
How to join
- Install the BOINC client if you do not already have it.
- Attach to https://boinc.eternityathome.org/eternity/
- When the account page asks for an invitation code, enter
eternityathome - Set your CPU share and schedule in BOINC Manager as usual.
💡 Do not be put off by the invitation code. It is published openly on the project's front page and exists to stop automated account-creation scripts, not to restrict who can take part. It is the same approach SRBase has used for years as spam protection.
Early numbers
A snapshot of project status at 30 September 2026, 09:35 UTC:
| Measure | Reported value |
|---|---|
| Users with credit | 66 |
| Users with recent credit | 66 |
| Computers with credit | 218 |
| Computers with recent credit | 215 |
| Tasks ready to send | 3,202 |
| Tasks in progress | 10,481 |
| Current performance | 3,051.68 GFLOPS (about 3.052 TFLOPS) |
Source: project server status page, 30 September 2026. These figures change constantly as hosts join, leave and return work.
Sixty-six users. That is a small enough crowd that a single enthusiastic cruncher moves the needle, and it is the main reason we are writing this up now rather than in six months.
One point of confusion worth clearing up
This is not the old Eternity2.net. That was a separate BOINC project announced in July 2007 during the original prize period, offering participants a share of the US$2 million, and it has long since been listed among retired projects. The 2026 project describes itself as an open community effort and makes no claim of organisational continuity with it.
Links
- BOINC Synergy wiki article: https://boincsynergy.ca/wiki/Eternity_II
- Project site: https://boinc.eternityathome.org/eternity/
- Server status: https://boinc.eternityathome.org/eternity/server_status.php
- Message boards: https://boinc.eternityathome.org/eternity/forum_index.php
Four hundred and sixty-eight out of four hundred and eighty. Twelve edges left. If you have spare cores, point them here.