The Japanese publisher who helped popularise the numbers puzzle Sudoku, Maki Kaji, has died from cancer aged 69 in Japan.
Kaji, who was a university drop-out, later worked in a printing company before founding Japan’s first puzzle magazine for his own company, Nikoli, which announced his death on its website.
"Maki Kaji, who spread the love of puzzles in the world as 'Godfather of Sudoku', passed away at 10:54 PM on August 10, 2021, at home in Tokyo. The cause of death was bile duct cancer," Nikoli's statement read.
Kaji was originally inspired by an existing number puzzle to create the game he later named Sudoku, which is a contraction of the Japanese "suuji wa dokushin ni kagiru", which means “the numbers (or digits) must remain single."
In the classic logic-based, combinatorial number-placement puzzle, the objective is to fill a 9×9 grid with digits so that each column, each row, and each of the nine 3×3 subgrids that compose the grid contains all of the digits from 1 to 9 without repetition.
The difficulty of each puzzle is based on how many filled-in figures are in a grid at the start of the puzzle.
The game became popular around 20 years ago when international newspapers outside Japan started printing it in their games' sections. The first World Sudoku Championship was hosted by Italy in 2006.
As the success of the puzzle came unexpectedly, Kaji didn't take out a patent for sudoku, meaning he did not have the rights to the puzzle.