They started the craze for the logic-based puzzle, and now a quizmaster from Japan has finally been crowned World Sudoku Champion.
Kota Morinishi won the individual tournament at the ninth World Sudoku Championships in Croydon this week.
During the gruelling competition, which featured 180 competitors from 34 countries, participants compete in nine individual rounds and three team rounds before an overall winner was declared. Each round lasts for up to 45 minutes, during which time each competitor must complete around 20 puzzles.
Kota Morinishi, an architecture graduate from the University of Tokyo, won the championship by defeating Estonia's Tiit Vunk in a tense final, after completing the final five puzzles including diagonal and irregular Sudoku, in less than 18 minutes.
Speaking after winning Japanese team gold in the 2012 championship in Croatia, Kota said: "Sudoku is my main hobby. I have played since I was a junior high school student. As a Japanese, I'm very glad to win the world championship of Sudoku."
Gareth Moore, from WSC organisers the UK Puzzle Association, whose day job is writing puzzle books, said standards have been rising every year.
"The very best manage to complete each booklet of around 10 puzzles per round two minutes per puzzle on average, which is astonishing. That's probably quicker than copying the answers if someone gave them to you."
Team GB consisted of Mark Goodliffe, a seven-time champion of The Times crossword, Neil Zussman a former winner of the TV quiz show Blockbuster, Matthew Collins completed Team GB and David McNeil, a lecturer in electronics and electrical engineering at Queen's University Belfast and the highest home finisher just outside the top 30.
- Standard Sudoku has a 9x9 grid...
- ...But there are around 500 types of Sudoku that have been created since the puzzle's birth in Japan in the 1980s. The pinnacle for Sudoku masters is the 100x100 Sudoku grid
- Sudoku means "single-number" in Japanese
- This year is the first year the World Sudoku Championship has been played in the UK
- Japanese publisher Nikoli turned Sudoku into a global craze in the mid-1980s...
- ...But the Japanese didn't invent Sudoku. The grid – was designed by Howard Garns, a retired architect from Indianapolis in the US who died in 1989
- Some historians of Sudoku, however, hark back to Paris in the 1890s, when newspapers published "magic square" puzzles, with double digits (it's one to nine in Sudoku) and requiring some arithmetic to solve
- Some studies suggest that engaging in stimulating everyday cognitive activities such as solving puzzles like Sudoku, crosswords and playing card games reduces the risk of developing Alzheimer's disease.