I had the chance to meet him at the 2010 world sudoku championships, hosted that year in Philadelphia, USA. Always fond of games and gambling - Nikoli the puzzle company takes its name from Nikoli the racehorse - he hosted a couple of rounds of the Nikoli derby in which I was lucky enough to finish to second, winning a tenugui which I still have with me today.
Kaji was known as the “godfather of sudoku,” following his role in the worldwide explosion of its popularity in 2004.
I am tickled to see an example of a Masyu puzzle included on the BBC website (and also how much better designed it used to be!). But I come under the category of a puzzle fanatic. I think part of his puzzling greatness is reflected in this quote:
"The secret to inventing a good puzzle," he said, "is to make the rules simple and easy for everyone, including beginners."You have to be able to make both easy and difficult puzzles using the same rules."Between 200 and 300 people help to complete a new puzzle. It has to be something that children, old people and everyone in between can enjoy, to be really good."
Rest in peace.