I have to admit that I have not caught the fever that these puzzles seem to have generated.
Most every newspaper in the world has started publishing these brain teasers.
"Sudoku , sometimes spelled Su Doku, is a logic based placement puzzle, also known as Number Place in the United States. The aim of the canonical puzzle is to enter a numerical digit from 1 through 9 in each cell of a 9x9 grid made up of 3x3 subgrids (called "regions"), starting with various digits given in some cells (the "givens"). Each row, column, and region must contain only one instance of each numeral.
Completing the puzzle requires patience and logical ability. Its grid layout is reminiscent of other newspaper puzzles like crosswords and chess problems.
Although first published in 1979, Sudoku initially became popular in Japan in 1986 and attained international popularity in 2005."