The Real History Behind 11 Logic Puzzles

Every game on Daily Grid belongs to a puzzle genre with its own real, documented history - some of it stretching back further than you'd expect, and at least two of these stories involve someone taking credit for an invention that wasn't theirs. Here's where each of the eleven actually came from, as best as puzzle historians have been able to pin down.

Bridges (Hashiwokakero): a chemistry diagram in disguise

Bridges is the Western name for Hashiwokakero ("build bridges"), which first took shape in the Japanese puzzle magazine Puzzle Communication Nikoli - a prototype ran in issue 28 in December 1989, and the finished ruleset debuted in issue 31 in September 1990. It was submitted by a reader writing under the pen name "Lenin," a student at the time, who has said the idea came from staring at molecular bonding diagrams in a chemistry class - single and double bonds between atoms looked a lot like single and double bridges between islands. The puzzle's working title was even Ketsugo-shu, meaning "atomic bonding," before it was renamed to its bridge theme.

Play it yourself: today's Bridges puzzle · how to solve it

Perimeter (Slitherlink): the same inventor, a different shape

The same Nikoli reader behind Bridges is also credited with Slitherlink, the single-loop puzzle Daily Grid calls Perimeter. It appeared even earlier, in Nikoli issue 26 in June 1989, formed by merging that reader's rule idea with a second contributor's related concept. The very first published versions put a number in every square rather than the sparse clues used today - the sparser, harder version we all know now came later, after readers had gotten the hang of the rule.

Play it yourself: today's Perimeter puzzle · how to solve it

Parcel (Shikaku): invented by a math student, not a company

Parcel is Daily Grid's version of Shikaku ("cut into rectangles"), invented in 1989 by Yoshinao Anpuku, a mathematics student at Kyoto University, and published shortly after by Nikoli. It's one of the cleanest examples of a puzzle designed by a single outsider rather than an in-house team - a two-rule idea (one number per rectangle, number equals area) that turned into a genre still appearing in newspapers worldwide, including as "Cellblocks" in The Guardian.

Play it yourself: today's Parcel puzzle · how to solve it

Tiles: 150 years old, and stolen from its real inventor

The sliding 8-puzzle behind Daily Grid's Tiles is a scaled-down version of the famous 15 Puzzle, which sparked a genuine craze in the United States in 1880 before spreading to Europe within months. Its actual inventor was Noyes Chapman, a postmaster in Canastota, New York, who showed an early version to friends as far back as 1874 and unsuccessfully applied for a patent in 1880. Sam Loyd, a famous puzzle columnist, didn't claim to have invented it until 1891 - a full decade after the fact - but his fame made the false claim stick for over a century. Puzzle historian Jerry Slocum's research eventually set the record straight: Loyd had nothing to do with the puzzle's invention or its original popularity.

Play it yourself: today's Tiles puzzle · how to solve it

Bits (Binairo): invented twice, in two countries, the same year

Daily Grid's binary grid puzzle Bits is built on rules known internationally as Binairo or Takuzu. Both names describe the same puzzle, because it was invented independently by two different designers around 2009: Belgian duo Peter De Schepper and Frank Coussement, who published it as "Binairo" in a Belgian newspaper, and Italian designer Adolfo Zanellati, who had created a nearly identical ruleset called "Tohu-wa-Vohu." Neither knew about the other's version until after both had already caught on in their own countries - one of several cases in puzzle history where the same clean idea was discovered twice.

Play it yourself: today's Bits puzzle · how to solve it

Pathways (Numberlink): a legitimate Sam Loyd credit, for once

Pathways belongs to the Numberlink family, and its earliest known ancestor really was published by Sam Loyd - the same columnist who later fabricated his 15 Puzzle claim - in the Brooklyn Daily Eagle in 1897. English puzzle master Henry Dudeney printed a closer version in his 1917 book Amusements in Mathematics, using letter pairs instead of numbers. Nikoli popularized the format in Japan in 1987 under two names - Arukone for letter pairs, Nanbarinku for number pairs - and it found a second life in 2012 as the mobile game Flow Free, which has since been downloaded over 100 million times.

Play it yourself: today's Pathways puzzle · how to solve it

Snake: born from a school of fish, mid-dive

Daily Grid's Snake sits in the Hidato and Numbrix family of numbered-path puzzles. Hidato was invented by Gyora Benedek, an Israeli mathematician and computer scientist, who has described watching a school of fish dart around him while scuba diving and trying to mentally reconstruct their path from the moments they changed direction. Back on land, a soaked Sudoku puzzle in the shower gave him the format to build it in. Numbrix, a variant that restricts movement to horizontal and vertical steps only - the version Snake most closely follows - later ran in Parade magazine under puzzle icon Marilyn vos Savant's byline.

Play it yourself: today's Snake puzzle · how to solve it

Polyfit: the pieces are older than their own name

Polyfit is built on polyominoes - shapes made of connected squares - a term coined by mathematician Solomon Golomb in a 1953 lecture to the Harvard Mathematics Club. But the puzzles themselves are older than the name: English puzzle writer Henry Dudeney had already published a five-square "pentomino" problem back in 1907, and dissection puzzles using the same shapes ran in a British puzzle journal through the 1930s and 40s. Golomb's work didn't reach a wide audience until Martin Gardner wrote it up for Scientific American in 1957, the article that turned polyominoes into a recreational-math staple.

Play it yourself: today's Polyfit puzzle · how to solve it

Conduit: the puzzle that outgrew a Flash game

Conduit's rotate-a-tile-to-connect-the-network mechanic comes from a puzzle genre usually called Net, FreeNet, or NetWalk. Programmer Simon Tatham built the best-known open-source version around 2005 after playing an earlier Flash game called FreeNet, written by Pavils Jurjans - Tatham's implementation became the first puzzle in his widely used Portable Puzzle Collection. The classic genre asks you to connect every tile into one loop-free network; Conduit adapts the idea with its own win condition, powering three specific exits rather than requiring every pipe on the board to join in.

Play it yourself: today's Conduit puzzle · how to solve it

BlindSlide: a 1970s parking lot, with a new twist

BlindSlide's block-clearing setup shares its DNA with Rush Hour, the sliding-block puzzle Japanese inventor Nob Yoshigahara created in the 1970s under the working title "Tokyo Parking." Binary Arts (later renamed ThinkFun) licensed it from him in 1995 and released it in the US in 1996, where it went on to sell more than 50 million units. Daily Grid's twist is its own: instead of sliding blocks in real time, you queue every move first and only then watch the whole plan play out - closer to programming a robot than parking a car, which is why an automatic rewind, not a redo button, is how you learn from a wrong plan.

Play it yourself: today's BlindSlide puzzle · how to solve it

Logice: the one genre with no real inventor - and a famous fake one

Logic-grid deduction puzzles like Logice don't trace back to a single Nikoli issue or a named inventor the way the others on this list do - the format was refined gradually across decades of puzzle magazines, most notably Dell's long-running logic puzzle line. The genre does have one famous false-attribution story of its own, though: the "Zebra Puzzle," first published anonymously in Life International in December 1962, is still widely called "Einstein's Riddle" today, supposedly invented by Albert Einstein as a boy. There's no evidence he had anything to do with it - one giveaway is that the original puzzle mentions a cigarette brand that didn't exist until Einstein was already in his fifties.

Play it yourself: today's Logice puzzle · how to solve it

What this history has in common

A striking number of these puzzles came from one person with a simple idea rather than a studio or a committee - a chemistry student, a postmaster, a scuba diver, a math undergraduate. Where credit went wrong, it went wrong the same way twice: someone famous claimed an invention decades after the fact, and the myth outlived the correction. It's part of why Daily Grid is built the same way its ancestors were - one person, no guessing required, and a fresh set of puzzles every day for you to add to that same long, slightly chaotic history.