New Delhi: Japan's Maki Kaji, the "godfather" of the cult favourite puzzle game Sudoku, died at the age of 69. He had been suffering from cancer, media reports said.
"Known as the Godfather of Sudoku, he was adored by puzzle lovers around the world and we would like to express our gratitude to all of you," Nikoli, his company, said on its website on Monday.
Kaji was a puzzle enthusiast himself and a publisher who created Japan's first puzzle magazine.
Maki Kaji was a college dropout who worked at a printing company before he founded the quarterly magazine.
Sometime in the mid-80s, he took inspiration from an existing numbers puzzle game and created Sudoku, Japanese for “every number must be single”.
"I get really moved when I see a new idea for a puzzle which has lots of potential," he told the BBC in 2007, adding that the secret to inventing a good puzzle was to make the rules simple.
"It is like finding treasure. It's not about whether it will make money, it is purely the excitement of trying to solve it."
Sudoku is a logic puzzle that challenges people to fill a grid of 9X9 blocks. There are nine boxes in each block. All columns, both vertical and horizontal, too have nine boxes each and must contain the numbers 1 to 9 without repetition. The number of filled-in figures for a grid at the start of the puzzle determines how difficult it is.
About two decades ago, Sudoku became popular outside Japan, as newspapers started printing them, usually alongside crossword puzzles. Known to keep mental faculties sharp if played regularly, the game is believed to be played by about 100 million people on a regular basis around the world.
The game became so popular that a world championship began in 2006 and has been held annually since.
According to a report in Reuters, Kaji continued to improve his puzzles with the help of the readers of his magazine. Due to ill health, he decided to step down as the company's chief in July and died on on August 10, 2021. He had bile duct cancer, the report said.