In this relatively cash rich, time poor society, the growing addiction to Sudoku may seem baffling. Why are busy people so keen to put off the e-mails, the shopping, even the evening drink, to hunch over the newspaper pencilling tiny digits into little boxes? What is the devilish attraction to puzzles labelled “fiendish” or, with the Killer Sudoku launched in The Times today, “deadly”? We are clearly a nation of fanatical logicians. Like the Rubik’ s cube, Sudoku rewards pure reasoning, not general knowledge. It produces sublime patterns of numbers, but does not require mathematical ability. The single path of logic seems to be so satisfying to the British psyche that it has already spawned its own national championships. And true to the spirit of British invention, the internet is already alive with home-made algorithms that promise to solve the trickiest Japanese combinations. Perhaps we are, after all, a nation of nerds.

The Times is proud to have introduced this phenomenon to Britain less than a year ago. We are not abashed by the many imitations, though we warn readers to beware the pseudoku. We are awed by the way that these crosswords without words seem to have crossed the generations to become a family activity.

Unlike Rubik’s cube, which was constrained by its physical shape, the newspaper puzzles can spawn new variants. The Samurai Sudoku forced readers literally to think outside the box. The five Killer Sudoku published today add a tantalising twist by joining the dots. Those who can travel beyond the “tricky” will gain much sudo kudos. For a Times reader, it should be a doddle.