I was sitting on the Bangkok Skytrain the other day, travelling through five stations on my way home from work, when I looked up and found an admiring glance opposite. The gentleman in question was obviously not leering at my countenance, but was rather nodding in genuine appreciation at the book I held in my hand. I was completing a Killer Sudoku to pass the time, and when he saw me notice him looking, he held up his own Kakuro Sudoku book for me to admire. As true professionals do, we nodded our heads in mutual respect and got back to work.
In 1997 Wayne Gould from New Zealand found a puzzle in a Japanese bookshop and went on to develop a computer program to develop the puzzles quickly. He went to The Times newspaper in Britain and convinced them to publish them daily, right next to the famous crossword. This was in 2004, and since then, the puzzle has taken over the world. You are almost as likely to find someone on the back of a donkey in Outer Mongolia scratching in pencil marks on a half completed Sudoku grid as you are to see a business man doing the same thing on the Tube in rush hour in central London.
The objective of classic Sudoku is to fill a 9×9 grid with digits so that each row and each 3×3 sub grid contain all the digits from 1-9. There will always be some numbers already in the puzzle to start you off. Realising early on that just like other types of puzzles, Sudoku has easier and more difficult variants; newspapers began to publish puzzles which were graded by difficulty. This means that when I pick up a newspaper with a gentle or moderate puzzle I can turn my nose up at it and not even attempt something so ridiculously patronising. However, when I find a puzzle graded tough or even diabolical I know I can sit down and write a good hour out of my day. Pure joy!
But I have moved on from the classic Sudoku. I found it limiting. I found it stifling and unsatisfying. Now I have discovered the Killer. This is a variant on Sudoku, but includes a mathematical component whereby the 9×9 grid is divided into regions, each with a number that the sum of all numbers in the region must add up to. Im not describing it very well, but if you find one of the books that publish these puzzles you can see for yourself.
Kakuro is another puzzle which I am not going to try to explain here for fear of either tying myself in knots or creating an article which is over 53 pages in length. Suffice it to say that it also has more of a mathematical character and is more challenging than the classic Sudoku.
I have now cracked the Killers more or less, and am ready to move on to something with even more edge. I am deciding between KenKen, Hidato, and the tantalizing Sudoku Cube. Oh yes, the Sudoku Cube will let me revisit my childish obsession with the Rubiks Cube and team it with my adult Sudoku fixation. Not only that, it will move me away from paper and pen or the computer and give me something to hold and twist and manipulate while walking down the street or sitting on the train and I can already see boring work meetings being enlivened by furtive Sudoku Cube tactics under the desk. What more could a Sudoku addict ask for?