Classic Puzzles

Every classic puzzle we have written about, grouped by how it works. Where we have built a solver, it sits next to the guide.

Burrs and interlocking puzzles

The Lu Ban Lock
The oldest interlocking puzzle is a building technique with the building removed. Everything in the burr family descends from a carpenter's joint.
The 6-Piece Burr Solver
Six notched sticks, one of which slides straight out. Here is the structure, the two hints that solve it, and the exact assembly sequence.
The 6-Piece Star
Five pieces go in beautifully and the sixth will not fit, no matter how you turn it. That is not you being bad at puzzles - it is the puzzle working exactly as designed.
The Altekruse
A man whose surname means old cross patented a cross-shaped puzzle in 1890. Experienced burr solvers routinely lose their first half hour to it.
Kumiki
A carpentry method invented because metal fasteners fail in earthquakes, later shrunk down into toys shaped like animals and pagodas.

The Soma Cube Solver
Piet Hein worked it out during a physics lecture in 1933. Seven pieces, twenty-seven cubes, and 240 different ways to finish - which is exactly why the modern versions take the same pieces and add a rule.
The Snake Cube Solver
You probably have one on your desk right now, unfolded and looking like a mess. Here is the folding logic, with a video if you would rather watch.
The Bedlam Cube
Thirteen pieces, a 4x4x4 cube, and 19,186 correct answers. It is still one of the hardest assembly puzzles ever sold, and the number of solutions is why people underestimate it.
Pentominoes Solver
There are exactly twelve pentominoes. Not twelve that anyone has found, twelve that can exist, and the proof is something you can do yourself on squared paper.
Tangram Solver
The tangram is the most widely taught mechanical puzzle in the world. It is also, almost always, taught with a history that is not true.
The T Puzzle
Four pieces, one letter T, and a success rate that embarrasses people. Companies gave them away for a reason: nobody could do it, and everybody kept trying.
The Stomachion
A puzzle designed in the third century BC, erased in the tenth, recovered in the twentieth, and finally counted in 2003.
Happy Cube
Flat foam that folds into a cube with no glue and no frame. The grid behind the shapes is the reason it holds together at all.

The Rubik's Cube Solver
Forty-three quintillion arrangements, and every single one of them is at most twenty moves from solved.
The Gear Cube Solver
A twisty puzzle whose first production name was a warning about getting your fingers caught.
The Void Cube Solver
Take the middle out of a Rubik's Cube and it still turns. It also gains a position the original cannot reach, which is where people get stuck.
The Mirror Cube
One colour, nine different sizes, and a surface that goes lumpy the moment you scramble it.
Square-1
Every other twisty puzzle stays the shape it started. This one turns into something unrecognisable on the second move, and that is the design working.
The Pyraminx Solver
A tetrahedron with four corners you can solve by accident. Strip those away and only 11,520 positions are left, which is why beginners finish it.
Hungarian Rings
It arrived in the Rubik boom and looks the part. An American patent from 1893 describes the same mechanism, ninety years early.
The Missing Link
Ideal followed the Rubik's Cube with a puzzle whose middle rows do not turn. That one restriction is the entire difficulty.
Rubik's Snake
Ernő Rubik's second famous puzzle has no solution at all. That is not a flaw, it is the design, and it is why people confuse it with a puzzle that does.
Shashibo
A cube with no solved state, held together by magnets rather than geometry. It is the best-selling puzzle object of the moment and barely a puzzle.

The 15 Puzzle Solver
Sam Loyd spent twenty years claiming he invented the 15 puzzle. He did not.
Huarong Dao
A general escaping through a mountain pass, rendered as ten wooden blocks. The shortest escape takes 81 moves, and it took until 1964 to find out.
Sliding Block Puzzles
Nothing is hidden and every move is visible. Sliding block puzzles are still among the hardest things in the field, and the mathematics says so.
The Tower of Hanoi Puzzle Solver
Three pegs, a stack of disks, move them over there. It looks almost too simple to be interesting - until you work out how many moves it actually takes.
Peg Solitaire Solver
Two boards that look almost identical. One can be solved in eighteen moves.
Perplexus
A steel ball, a clear sphere, and a hundred obstacles on a single track. There are no wrong turns in it at all, which is not the same as being easy.

Chinese Rings Solver
Most puzzles are solved by insight. The Chinese rings is solved by counting, and the counting system it uses was not formally described for another four centuries.
Blacksmith Puzzles
Two pieces of bent iron, linked. Nothing is hidden, nothing moves except the pieces themselves, and most people never get them apart.
Gordian's Knot
A plastic puzzle sold in toy shops is a Dutch designer's research result, and the move count printed everywhere is one short.
Hanayama Cast Puzzles
The most widely owned line of mechanical puzzles in the world, rated one to six, designed by some of the best people in the field, and sold for pocket money.
Puzzle Rings
Four to twelve bands that collapse the moment you take the ring off. The famous story behind it is charming and almost certainly invented.

Japanese Puzzle Boxes
A box with no hinge, no lock and no latch. The pattern on the outside is not decoration: it is camouflage for the seams you need to find.
Trick Locks
A lock whose keyhole is a decoy. The honest ones are two thousand years old, and the marketing around them is frequently nonsense.
The Cryptex
The cryptex is routinely sold as a Leonardo da Vinci invention. It was invented in 2003, by a novelist, for a thriller.
Revomaze
A metal cylinder with a maze cut inside it that you will never see. The only feedback is a pin that drops when you fall into a trap.
Impossible Bottles
A padlock inside a sealed bottle with a neck too small to admit it. The man who made the best of them never told anyone how, and died with the methods.
Chinese Puzzle Balls
Twenty-five spheres inside one another, every layer carved through holes from the outside.

Magic Squares Solver
There is exactly one 3x3 magic square. Not one that is best known, one that exists.
Matchstick Puzzles Solver
They feel like folk puzzles passed down for centuries. They were invented as school exercises in the 1860s, and one man in 1957 made them famous.
Instant Insanity
Four cubes, four colours, and one correct stack. Trial and error has 331,776 arrangements to wade through.