Sudoku has been around for years, but only in 2005/2006 has it gained a captive worldwide audience. The rules are simple: fill in the missing numbers within the diagram with a digit between 1 and 9. However, each row, column, and region (one of nine sub-grids within the whole diagram) can contain the digits 1 thru 9 only once. You get a few digits already placed within the diagram, but the rest is up to you.