Su Doku: The puzzle that ate the world

It looks like just another numbers game. The kind usually found in puzzle books that prop up tables in old people's homes and doctors' waiting rooms. But peer closer, and your way of life will be in jeopardy. For this is Su Doku and it is sweeping across the country like a virulent strain of avian flu.

It looks like just another numbers game. The kind usually found in puzzle books that prop up tables in old people's homes and doctors' waiting rooms. But peer closer, and your way of life will be in jeopardy. For this is Su Doku and it is sweeping across the country like a virulent strain of avian flu.

The game has stealthily taken a grip on the UK over the past few months, turning previously normal people with active social lives into hermits who would rather stay at home and stare down at a little grid scattered with numbers. Commuters who once ranted at ticket collectors now patiently hope their trains will be late so they can complete a challenge. Bored office workers are quietly logging off their computers and returning to pencils and paper. Classrooms full of teenagers have gone eerily quiet.

All they are trying to do is fill out rows and boxes with the figures one through to nine without duplicating them. But it seems that the task is both cryptic and highly addictive. The thinking person's crack cocaine has arrived on our shores. A desperate need for a daily fix is met by newspapers such as The Independent, but some people are still not getting enough.

Internet chatrooms are filled with Su Doku debate and hints on where to find new grids. The problem is, the better that players become the quicker they can complete the tasks. As one addict on the London Underground told me: "At first it would take me a fair bit of the day to get through the puzzle printed in the newspaper, but I'm now doing them in 15 minutes. So I'm done by early morning, but I've got a taste for it for the rest of the day. The whole thing is really gripping, but intensely frustrating."

Help, however, is at hand for those would-be grand masters of Su Doku. For today The Independent takes the puzzle to a new level, with the launch of Super Su Doku. More boxes and the introduction of letters as well as numbers should ensure that the golf courses and shopping malls are quiet this weekend.

Not since Rubik's Cube invaded Britain in the Eighties has the country been so transfixed by a new style of puzzle. And while thousands of us opted for the screwdriver approach then, there's no easy way out this time. Electronics companies are scrambling to create a version for mobile phones, and pocket computers have already been loaded up with it. A board game is said to be in the pipeline while production companies are figuring out how to transfer it to television. The Countdown presenter Carol Vorderman has praised the number game, saying that she is "absolutely hooked". The 44-year-old added: "Once I've put the kids to bed, all I want to do is get down to a number puzzle. I've become a bit of a saddo.

"I have competitions with friends to see who finishes first. I go for the fiendishly hard one and have got my time down to one hour, 10 minutes."

She's not the only celebrity to have been snared. The Independent's columnist Howard Jacobson admits the habit is "back in his life". On The Independent's new puzzles he says: "I have been going to great lengths to avoid Su Doku wherever else it appears, but now I have no hiding place."

And it's all the fault of the Japanese. Yes, not content with getting adolescents hooked on electronic games they're now targeting the rest of the population.

Su Doku roughly translates as "the number that is single" and was introduced to Japan by a magazine in the late 1980s. It has grown to become the most popular task in a puzzle-obsessed country. Five publicationsproduce Su Doku-style challenges every month.

However, it is thought the roots of Su Doku go back further, to an American publication which printed similar brain-teasers based on an 18th-century test called Latin Squares, developed by a Swiss mathematician, Leonhard Euler.

But the aficionados of modern-day Su Doku are keen to point out that it is not a mathematical problem. Logic is what's required and those who find the appearance of figures intimidating should relax.

The man behind The Independent's new challenge is Mark Huckvale, a senior lecturer in linguistics at University College London. "No mathematical calculation at all is involved in this. I think some people are a bit frightened when they see numbers. But they could be colours or, as in today's grid, letters."

Su Doku is about finding symmetrical patterns on the page and it appeals to the addictive aspect of our brains. But the game also prompts thought patterns that can prove therapeutic and it has been suggested that, as a test of logic, it can slow the progression of conditions such as Alzheimer's. It has already proved to be a source of comfort for those suffering short-term illness.

That has been the case for Elaine Hindle, 33, who works for the Medical Research Centre at the University of Glasgow. She was recently diagnosed as suffering from chronic fatigue syndrome. "The first couple of weeks were a total nightmare," she said. "It wasn't just being really tired that was getting me down as having nothing to do. I was also really worried that my mind was going into hibernation."

Her doctor recommended that she keep busy by reading and doing crosswords. "I was never much of a one for crosswords. I started doing them anyway, but didn't find them particularly gripping. Then I discovered Su Doku.

"I've been doing it every day since and the transformation has been incredible. I'm hooked and can't put them down until they are complete. Some can be quite easy and you can finish them in minutes, but others have you tearing your hair out."

"I'm feeling much better and am getting out more. I bought a Su Doku book and it goes everywhere with me in my handbag. I can't put the thing down. I'm hooked. But it has also really helped me mentally.

"Doing Su Doku is like getting a daily mental workout. It's sharpened me up no end. The trouble is going to come when I have to go back to the office - I don't know how I'll drag myself away from them to work." It seems just a matter of time before we are reading reports about how many hours employees are spending on the puzzles while at work. An employee of a major international financial institution confided to me that he had spent an entire working week glued to Su Doku squares. "The project I was working on was put on ice for a week," the 32-year-old accountant said. "I just couldn't stop myself and the boss had a word with me. I came clean and told him about Su Doku. Now he's at it too." Converts confess that it takes enormous discipline to avoid spending all day - and night - ploughing through puzzles. "I would really like my life before Su Doku back!" joked Bernard Stay, 71, from St Albans.

"I never thought I had an addictive personality, but Su Doku is definitely bad for me. If I don't complete a puzzle before noon I get suicidally depressed for the rest of the day and even lose sleep fretting on what I've missed."

And the Su Doku master who is about to lift its followers to a new high admitted he was surprised at how quickly it had caught on. "I guess it is pretty odd," Mr Huckvale said. "A couple of months back I knew nothing about this and suddenly it is everywhere."

He explained that he was introduced to the puzzle through his wife. "She got into Su Doku through a newspaper she picked up at work." Soon she was flying through them and ran out of grids.

"I thought it sounded rather interesting and came up with a computer programme to generate new grids. I printed them out and she's doing them in bed now - instead of reading a book."

And now, thanks to the same computer program, comes Super Su Doku, which is exclusive to The Independent print edition. "The main thing people will notice is that it's more difficult," warns Mr Huckvale. "In fact, when you expand the grid it can be very, very difficult. Mind-boggling. While it might be possible to complete some of these in half an hour, others could take days."