Sudoku

French newspapers featured similar puzzles in the 19th century, and the modern form of the puzzle first appeared in 1979 puzzle books by Dell Magazines under the name Number Place. However, the puzzle type only began to gain widespread popularity in 1984 when it was published by the Japanese puzzle company Nikoli as "Suuji wa dokushin ni kagiru" (the numbers must be single), and in 1986 Maki Kaji (鍜治 真起, Kaji Maki), the president and co-founder of Nikoli, shortened the name to Sudoku, where "su" is number and "doku" is single. In newspapers outside of Japan, it first appeared in The Conway Daily Sun (of North Conway, New Hampshire) in September 2004, and then The Times (of London) in November 2004, both using puzzles generated by a computer program written by the former Hong Kong judge Wayne Gould, who had encountered the puzzles when visiting Tokyo.

History

Predecessors

Number puzzles appeared in newspapers in the late 19th century, when French puzzle setters began experimenting with removing numbers from magic squares. Le Siècle, a Paris daily, published a partially completed 9×9 magic square with 3×3 subsquares on November 19, 1892. It was not a Sudoku because it contained double-digit numbers and required arithmetic rather than logic to solve, but it shared key characteristics: each row, column, and subsquare added up to the same number.

On July 6, 1895, Le Siècle's rival, La France, refined the puzzle so that it was almost a modern Sudoku and named it carré magique diabolique ("diabolical magic square"). It simplified the 9×9 magic square puzzle so that each row, column, and broken diagonals contained only the numbers 1–9, but did not mark the subsquares. Although they were unmarked, each 3×3 subsquare did indeed comprise the numbers 1–9, and the additional constraint on the broken diagonals led to only one solution.

These weekly puzzles were a feature of French newspapers such as L'Écho de Paris for about a decade, but disappeared about the time of World War I.

Modern Sudoku

The modern Sudoku was most likely designed anonymously by Howard Garns, a 74-year-old retired architect and freelance puzzle constructor from Connersville, Indiana, and first published in 1979 by Dell Magazines as Number Place (the earliest known examples of modern Sudoku). The New York Times puzzle editor Will Shortz discovered in 2005 that Garns' name was always present on the list of contributors in issues of Dell Pencil Puzzles and Word Games that included Number Place and was always absent from issues that did not, resulting in the discovery of his role in the puzzle's invention. Garns died in 1989 before getting a chance to see his creation as a worldwide phenomenon. Whether or not Garns was familiar with any of the French newspapers listed above is unclear.

The puzzle was introduced in Japan by Maki Kaji (鍜治 真起, Kaji Maki), president of the Nikoli puzzle company, in the paper Monthly Nikolist in April 1984 as Sūji wa dokushin ni kagiru (数字は独身に限る), which can be translated as "the digits must be single", or as "the digits are limited to one occurrence" (In Japanese, dokushin means an "unmarried person"). According to a 2007 article by the BBC, Kaji had come across the puzzle in the Dell puzzle books published in the United States. Kaji created the abbreviated name Sudoku (数独), by taking only the first kanji of compound words to form a shorter version. Nikoli claims to hold trademark rights to the name "Sudoku" in Japan, and some other publishers use the name Number Place (ナンバープレース, Nanbāpurēsu) or, more informally, a shortening of the two words, Num(ber) Pla(ce) (ナンプレ, Nanpure). The puzzles are now published in mainstream Japanese periodicals, such as the Asahi Shimbun, as well as in puzzle books.

Spread outside Japan

In 1997, the recently retired Hong Kong judge Wayne Gould saw a Sudoku puzzle book in a Tokyo bookshop. Over six years, he developed a computer program to produce the puzzles and rate their difficulty.

The first newspaper outside of Japan to publish a Sudoku puzzle was The Conway Daily Sun (of North Conway, New Hampshire), which published a puzzle by Gould in September 2004. Gould's wife Gayle was a professor of linguistics at the local university.

Gould pitched the idea of publishing Sudoku puzzles to newspapers, offering the puzzles for free in exchange for the newspapers' attributing them to him and linking to his website for solutions and other puzzles.

Knowing that British newspapers have a long history of publishing crosswords and other puzzles, he promoted Sudoku to The Times in Britain, which launched it on November 12, 2004 (calling it Su Doku). The first letter to The Times regarding Su Doku was published the following day on November 13 from Ian Payn of Brentford, complaining that the puzzle had caused him to miss his stop on the tube. Sudoku puzzles rapidly spread to other newspapers as a regular feature.

The rapid rise of Sudoku in Britain from relative obscurity to a front-page feature in national newspapers attracted commentary in the media and parody (such as when The Guardian's G2 section advertised itself as the first newspaper supplement with a Sudoku grid on every page). Recognizing the different psychological appeals of easy and difficult puzzles, The Times introduced both, side by side, on June 20, 2005. From July 2005, Channel 4 included a daily Sudoku game in their teletext service. On August 2, the BBC's program guide Radio Times featured a weekly Super Sudoku with a 16×16 grid.

The world's first live TV Sudoku show, Sudoku Live, was a puzzle contest first broadcast on July 1, 2005, on the British pay-television channel Sky One. It was presented by Carol Vorderman. Nine teams of nine players (with one celebrity in each team) representing geographical regions competed to solve a puzzle. Each player had a hand-held device for entering numbers corresponding to answers for four cells. Phil Kollin of Winchelsea, England, was the series grand prize winner, taking home over £23,000 over a series of games. The audience at home was in a separate interactive competition, which was won by Hannah Withey of Cheshire.

Later in 2005, the BBC launched SUDO-Q, a game show that combined Sudoku with general knowledge. However, it used only 4×4 and 6×6 puzzles. Four seasons were produced before the show ended in 2007.

As the popularity spread in Britain, it spread to the United States as well, and by mid-2006, nearly every major newspaper in the United States was publishing a daily Sudoku puzzle. An annual World Sudoku Championship series has been organized by the World Puzzle Federation since 2006, except in 2020 and 2021 during the COVID-19 pandemic.

Sudoku software is very popular on PCs, websites, and mobile phones. It comes with many distributions of Linux. The software has also been released on video game consoles, such as the Nintendo DS, PlayStation Portable, the Game Boy Advance, Xbox Live Arcade, the Nook e-book reader, Kindle Fire tablet, several iPod models, and the iPhone. Many Nokia phones also had Sudoku. In fact, just two weeks after Apple Inc. debuted the online App Store within its iTunes Store on July 11, 2008, nearly 30 different Sudoku games were already in it, created by various software developers, specifically for the iPhone and iPod Touch. Sudoku games also rapidly became available for web browser users and for basically all gaming, cellphone, and computer platforms.

In June 2008, an Australian drugs-related jury trial costing over A$1 million was aborted when it was discovered that four or five of the twelve jurors had been playing Sudoku instead of listening to the evidence.