Sudoku is an addictive number placement game that was
popularized in Japan and is now played by millions around
the world. The puzzle is carried alongside the crossword in
many daily papers. To solve Sudoku simply fill in
all the squares with the digits 1 through 9 such that every
row, column and 3x3 block contains all the digits 1 through
9. So the same digit may never be placed more than
once in the same row, column, or 3x3 block. Some numbers
are already filled in for you, use these as your starting
point. In a true Sudoku there is only one possible way to
fill in the grid and all moves may be derived from logic.
However some people find guessing a good solving technique
if done carefully.
There is a wealth of information on the Internet about
Sudoku, a good starting point is the Wikipedia entry. Another popular site
is Michael Mepham's Sudoku Online where he has a daily
Sudoku puzzle contest.