To be frank, I highly doubt anyone will ever solve our version of this puzzle without outside help.
That is not a sales line. The version most people have met came assembled in a box with a solution booklet. Ours arrives as six loose boards and nothing else.
Extreme Torture - Quick Summary
Extreme Torture is a six-piece separated board burr designed by Frans de Vreugd in 2002. It takes 70 moves to take apart - burr level 28-22-9-8-3 - the hardest form found in de Vreugd's research. Expert difficulty, 4+ hour solve time. Ships disassembled.
Best for: solvers who have finished the hard puzzles in their collection and want something that will genuinely beat them for a while, and collectors who measure a puzzle by how long it held out.
70 Moves
De Vreugd did not design this by hand. He fed separated board burrs into Burrgrower, a program written to raise the level of a puzzle - first drafted by Dic Sonneveld and rewritten in C++ by Goh Pit-Khiam, whose own packing puzzles we carry. Extreme Torture is what came back.
The level notation reads 28-22-9-8-3: twenty-eight moves just to free the first board, then twenty-two more for the second, then nine, then eight, then three.
Nothing about it yields early. You can make twenty correct moves and have nothing visible to show for it.
The Scale of the Search
De Vreugd published the numbers himself. He narrowed the design space to eleven usable board shapes, which give 8,008 possible six-piece sets. Those sets can be fitted together in 1,364,932 ways.
Only 2,394 of those can be taken apart again - 0.18%.
That is the context this puzzle sits in. Almost everything that looks like a solved board burr is a dead end, and Extreme Torture is the hardest thing that survived the search.
Where the Design Came From
It started with a suggestion. Jim Gooch told de Vreugd that you could take a standard six board burr and pull the two boards in each pair one unit apart. De Vreugd wrote a search to find piece sets that would still assemble. ZigZag came out first, then Torture at level 17.4, and then he made one last push with the software. Extreme Torture is the end of that road.
Sold for Years as Gordian's Knot
This design went into commercial production in 2002 under the name Gordian's Knot, made by ThinkFun, now part of Ravensburger. That is where most people ran into it, on a toy shop shelf rather than in a puzzle collection. It has since been discontinued.
Greg Puzzles is not affiliated with ThinkFun or Ravensburger. We list the design under the name Frans de Vreugd gave it, and ours comes out of the box in pieces.
It Arrives in Pieces
This puzzle ships disassembled, and that is deliberate. Assembly is the challenge, and handing it to you already solved would remove the entire point. It also means you are working those 70 moves in reverse, with no solved reference state to copy and no photograph to work backwards from. You get six boards and the knowledge that they fit.
Expect to put it down and come back to it. Most people do.
If you would rather work up to this one, all three are sold together as the Separated Board Burr Set.
Frequently Asked Questions
How many moves does Extreme Torture take?
70 moves to disassemble. The burr level is 28-22-9-8-3 - the first board alone takes 28 moves to free.
Does Extreme Torture arrive assembled?
No. It ships disassembled, as six separate boards. Assembling it is the puzzle - a solved puzzle in the box would be no puzzle at all.
How hard is Extreme Torture?
Expert, and at the top of that band. Plan on four hours or more spread across more than one sitting, and do not treat it as a reasonable first attempt at interlocking designs. It is the hardest form found in de Vreugd's research.
Is Extreme Torture the same as Gordian's Knot?
It is the same design. Frans de Vreugd named it Extreme Torture in 2002, and it went into commercial production that year as Gordian's Knot, which has since been discontinued. We use the designer's original name.
Who designed Extreme Torture?
Frans de Vreugd, a Dutch puzzle designer, in 2002, working from Jim Gooch's separated board burr idea and using Burrgrower, the level-raising software written by Dic Sonneveld and Goh Pit-Khiam.
