Maki Kaji, a university dropout who turned a numbers game into one of the world's most popular logic puzzles and became known as the "Godfather of Sudoku," died Aug. 10 at his home in Tokyo. He was 69.
His death was announced Tuesday by Nikoli, the puzzle company he co-founded. The company said in a statement that the cause was bile duct cancer.
In a speech in 2008, Kaji said he first "fell in love" with a game called Number Place in 1984. He renamed it sudoku.
"I wanted to create a Japanese name," he said. "I created the name in about 25 seconds."
The reason: He had been in a rush to get to a horse race. He said he had not expected the name to stick. ("Sudoku" roughly translates to "single numbers.")
By then, with two childhood friends, he had started the company that would later become Nikoli, which says it is among the most prolific global publishers of puzzle magazines and books. Nikoli helped catapult sudoku into the mainstream in the mid-2000s, publishing what it said was Japan's first puzzle magazine.
The company itself does not create many new puzzles — for example, an American is believed to have invented an earlier version of sudoku. But the game's true origins are murky. Some trace it back to Leonhard Euler, an 18th-century Swiss mathematician. Others say the idea came from China, through India, to the Arab world in the eighth or ninth century.
However the puzzle was created, Kaji's company made sudoku and other similar puzzles globally popular. Nikoli's secret, he told the New York Times in 2007, was that it largely tested and perfected existing puzzles.