Puzzle enthusiast and Sudoku legend, Maki Kaji has died of bile duct cancer at the age of 69, his company Nikoli Co. announced.

After dropping out of university, Mr Kaji worked at a printing press before starting Japan’s first puzzle magazine and finally inventing sudoku – an abbreviation of the Japanese for “every number must be single” – in the mid-80s, based on hints from an existing numerical puzzle.

The cognitive game requires participants to fill a grid of 9×9 blocks, each having nine boxes, with the numbers one to nine in all columns, vertically and horizontally, without repetition. The difficulty of a puzzle is determined by the amount of filled-in figures in the grid at the start.

After a fan presented it to the British newspaper The Times, sudoku became a worldwide success two decades later.

According to his company, Mr Kaji has been to more than 30 countries to share his love of puzzles.

Millions of people have participated in sudoku tournaments, and his organisation has offered more original puzzles to media companies in Japan and beyond.