Sudoku is best described as a logic-based placement puzzle, where players enter a numerical digit between 1 and 9 in each cell of a 9x9 grid, which is made up of nine 3x3 grids, known as “regions”. Each number must only appear once in each row, column and region. These rules are reflected in the game’s Japanese name, Sudoku, which is short for “suuki wa dokushin ni kagiru”, roughly translates to “the digits must remain single”.

To crack the enigmas surrounding Sudoku, mathematical calculations are not involved, although the game deals with numbers. In fact, any nine distinctive symbols or colours can also be used to make the puzzle work.

Sudoku actually trains the players’ logical thinking instead of arithmetical skills. As such, some teachers are now recommending and encouraging pre-school children to play this puzzle game, along with a variety of other “traditional” puzzles. It is no wonder that toys and games industry players are capitalising on its market potential of the puzzle game.

Despite the Japanese name, Sudoku actually originated from the U.S. The logical puzzle was invented in 1974 by a U.S.-freelance puzzle constructor, Howard Garns. The puzzle only adopted its name when first printed in the Asahi Shimbun, one of the most-established newspapers in Japan in 1984.

Then, in 1997, when retired Hong Kong judge, Wayne Gould, saw a published Sudoku in Japan, he took a great interest in the game and decided to spend the next six years to develop a computer program to produce Sudoku puzzles quickly. Mr. Gould promoted Sudoku to the Times in England in 2004, and it became a daily feature in the paper since November that year. Seeing Sudoku’s rapidly-growing popularity, other daily papers followed suit soon after in a bid to boost the papers’ circulation figures. By mid-2005, five more major national papers in the U.K. also started publishing the puzzle game regularly.

Commenting on the game’s phenomenal growth in the U.K., Mr. Michael Mepham – a veteran specialist with 25 years experience in tailor-making crosswords and other puzzles for national newspapers and magazines, including the renowned giant general knowledge crossword in the weekend editions of the Daily Telegraph – said, “I’ve never seen anything in the puzzle industry that’s caused such a fuss. It’s just one of those things that catches on.” Sudoku has been credited for boosting and stabilising circulation figures of newspapers in the U.K.

Sudoku spread to the U.S. soon after to cast a truly international phenomenon. Long-time editor of the New York Times crossword puzzle, Will Shortz, described Sudoku’s growth as “crushing crossword puzzles in the United States”.

Adding to its dominance in newspapers around the world, Sudoku puzzle books and magazines have also taken off. Hundreds of these publications are already flooding the market – not only in the United States, United Kingdom and Japan, but also in many other continents.

According to book retailers in the U.K., this logical puzzle has stirred a sensation in the market, bringing considerable benefits and consumer enthusiasm to other puzzle books.

Sadie Perkins, a bookseller at Waldenbooks of South Portland, Maine in the U.K. commented, “Sudoku has brought many new people of all ages back into puzzles: crosswords, word searches and other similar things. The interest has always been there, but not on this scale.”

In the U.S., reports tell that Sudoku books accounted for 7% of bestselling trade list in 2005, with 5.7 million copies sold at bookstores across the nation. And in Japan, five publishers are reported to be publishing Sudoku magazines, with a total monthly circulation of over 660,000 copies.

Apart from appearing at various publications, Sudoku has also popped up in other formats, like the recently released Sudoku board games. Much like the game in the published form, “Sudoku – the Ultimate Puzzle Game!” allows the player the opportunity to work out the solutions using 81 double-sided number tiles. The player only needs to follow the steps in an instruction booklet to set up the initial tiles to begin.

Of course, in today’s digital world, Sudoku has also found its way into the games software industry. Two most-prominent games have been released by Japanese computer games giant, Nintendo, in mid-2006.

Hitting the market in April was the Brain Age: Train your Brain in Minutes a Day! Designed for the Nintendo DS console, this game presents a series of mental challenges that keep the players’ brains active and excited, and it includes over 100 Sudoku puzzles.

Another invention from Nintendo was the Sudoku Gridmaster game, which was released in late-June 2006, just in time for the school summer holidays. This game contains 400-plus Sudoku puzzles in four levels of difficulty setting. This Nintendo DS game use touch-screen controls that make solving the puzzles faster and easier. The Sudoku Gridmaster game has installed features designed to assist players solve the puzzles. Market response has been highly positive for these Nintendo games.

On top of versions specially produced for game consoles, handheld Sudoku electronic gadgets have been in high demand in the market. A Hong Kong-based electronics supplier has released into the market a digital Sudoku game that is incorporated with a FM radio, which increases the appeal of this puzzle game considerably.

Furthermore, a number of online outlets are offering downloadable Sudoku software programs for other PC devices, including the increasingly popular PDA’s, Palm and other computers. According to Palm OS software online retailer, Palmgear, two different Sudoku games had occupied the second and third places in the best selling Palm OS software list in the first half of 2006.

Sudoku is gaining a foothold in the mobile phones market too. Finnish mobile phone producer, Nokia, is expected to release a brand new model which will include Sudoku games amongst other built-in features, in the fourth quarter of the year.