History

The puzzle was first published in New York in the late 1970s by the specialist puzzle publisher Dell Magazines in its magazine Math Puzzles and Logic Problems, under the title Number Place. The person who designed the puzzle and composed the first of its kind is not recorded, but it was probably Walter Mackey, one of Dell's puzzle constructors. The puzzle was introduced in Japan by Nikoli in the paper Monthly Nikolist in April 1984 as Suuji wa dokushin ni kagiru (数字は独身に限る), which can be translated as "the numbers must be single" or "the numbers must occur only once" (独身 literally means "single; celibate; unmarried"). The puzzle was named by Kaji Maki (鍜治 真起), the president of Nikoli. At a later date, the name was abbreviated to Sudoku (数独, pronounced SUE-dough-coo; sū = number, doku = single); it is a common practice in Japanese to take only the first kanji of compound words to form a shorter version. In 1986, Nikoli introduced two innovations which guaranteed the popularity of the puzzle: the number of givens was restricted to no more than 30 and puzzles became "symmetrical" (meaning the givens were distributed in rotationally symmetric cells). It is now published in mainstream Japanese periodicals, such as the Asahi Shimbun. Nikoli still holds the trademark for the name Sudoku; other publications (at least in Japan) use other names.

In 1989 Loadstar/Softdisk Publishing published DigitHunt on the Commodore 64, which was apparently the first home computer version of Sudoku. At least one publisher still uses that title.

Bringing the process full-circle, Kappa reprints Nikoli Sudoku in GAMES Magazine under the name Squared Away; the New York Post and USA Today now also publish the puzzle. It is also often included in puzzle anthologies, such as The Giant 1001 Puzzle Book (under the title Nine Numbers).

Curiously, Dell, the inventors of the puzzle, have made no attempts to cash in on this phenomenon.

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