On the whole, the difficulty level and types of the puzzles in this tournament put them at the top echelons of world-class competitions, Chen said.

There are over 40 forms in which the challenging game can be played, including con-ventional Sudoku, jigsaw Sudoku, killer Sudoku and skyscraper Sudoku. Fortress Sudoku, bridge Sudoku and puzzle Sudoku are the latest types of Sudoku variants introduced to China.

Promising future

BIST has been listed as one of the major world tournaments by the World Puzzle Federation (WPF). WPF is an international organization dedicated to the pursuit of puzzles. It is based in Brno, the Czech Republic. Some senior officers of WPF were invited to supervise the Beijing tournament and research possibilities for Beijing to hold the World Sudoku Championship in the near future.

Puzzle games similar to Sudoku have been played in China for thousands of years. Hetu and luoshu are two ancient Chinese games that challenge players to solve patterns of numbers.

Will Shortz, Chairman of WPF, spoke highly of BIST at the closing ceremony. He said the Beijing tournament was well organized and that China was bound to make great contributions to Sudoku.

Despite its short history, the Beijing tournament is already attracting top masters from around the world. Three world champions, including Snyder, Ondrousek, and Jan Mrozowski from Poland came to join the competition.

"We are so impressed by the Beijing tournament. As people can see, many top Sudoku players are gathered in Beijing for the championship," said Hana Koudelkova from the Czech Republic, who is a director of WPF.

"Sudoku has become popular in some countries, such as the United States, Germany, the Czech Republic and Japan. But at this moment, I would like to highlight China. This is the second year for Beijing to hold such a high-level annual tournament. We have seen a big move in every aspect of the event," she said.

At present, Beijing is planning to establish a Sudoku association in the second half of this year, aiming to provide service for a growing number of Chinese puzzlers and lay a foundation to one day host the WPC in China.

Zhang Zhaohui, General Secretary of Beijing Sports Federation, said to Beijing Review, "Beijing takes the lead in China's Sudoku development. With the establishment of the Beijing Sudoku Game Association, I believe more Chinese Sudoku masters will grow up in the near future as the Sudoku craze is heating up in Beijing."

What Is Sudoku?

Sudoku is a puzzle involving numbers with the essence that each number appears only once in each line and row of a grid. The standard Sudoku is a 9×9 grid that consists of nine 3×3 sub-grids. The puzzler needs to place numbers from one to nine into the blanks of a grid to complete the puzzle following certain rules. It is a logic-based game, and doesn't require a high educational level.

Modern Sudoku first appeared as a game called Number Place in the U.S. magazine Math Puzzles and Logic Problems in the 1970s. In 1984, it was introduced to Japan and soon became popular among people with the Japanese name "Sudoku." The game is easy to promote because people can play it with only a piece of paper and a pencil. Many newspapers and magazines have Sudoku puzzles to attract the attention of readers.

Currently, there are many Sudoku competitions around the world. The largest of them is the World Sudoku Championship (WSC), a top-level annual event sponsored by the World Puzzle Federation. The first WSC was held in the city of Lucca, Italy, in 2006.

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