Maki Kaji, a creator of the popular Sudoku number puzzle whose lifelong job was to spread the joy of puzzles, has passed away, his Japanese company said on Tuesday. He was 69 years old and suffered from biliary cancer.

Known as the “Sudoku Godfather,” Kaji created the puzzle to be easy for kids and others who didn’t want to think too much. Its name is made up of the Japanese characters for “number” and “single,” and players place the numbers 1 through 9 in rows, columns, and blocks without repeating them.

Ironically, it wasn’t until 2004 that Sudoku became a worldwide hit, after a fan from New Zealand introduced it and had it published in the UK newspaper The Times. Two years later, Japan rediscovered its own puzzle as “gyakuyunyu” or “re-import”.

Kaji was the general manager of his puzzle company, Nikoli Co., until July and died on August 10 at his home in Mitaka, a city in the Tokyo metropolitan area.

Maki has traveled to over 30 countries to spread his enjoyment of puzzles. The Sudoku Championships have drawn some 200 million people in 100 countries over the years, according to Tokyo-based Nikoli.

Sudoku has also never been a registered trademark, except in Japan, which has sparked its craze overseas, Nikoli said.

“Kaji-san coined the name Sudoku and has been loved by puzzle fans around the world. We are grateful from the bottom of our hearts for the patronage you have shown throughout its life, ”the company said in a statement.

Originally, Sudoku was called “Suji-wa-Dokushin-ni-Kagiru”, which translates to “The numbers should be single, single”. In recent years, Sudoku, considered the world’s most popular pencil puzzle, has been released in digital versions.

Born on the main northern island of Hokkaido, Maki started Japan’s first puzzle magazine after leaving Keio University in Tokyo. He founded Nikoli in 1983 and invented Sudoku around the same time.

Yoshinao Anpuku, who took over from Kaji as general manager of Nikoli, said Kaji made friends easily and had a “unique and playful approach to life.”

“Our mission is to pursue Maki’s vision and possibilities,” Anpuku said.

Nikoli has supplied original puzzles to over 100 media companies, including 10 foreign ones.

In its obituary, the leading Japanese newspaper Mainichi credited Kaji with starting puzzle sections in bookstores, as well as introducing the word “Sudoku” into the Oxford English dictionary.

Kaji is survived by his wife Naomi and two daughters. Funerals took place between relatives. A separate memorial service is being hosted by Nikoli, but details were still undecided.

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