AtfSudoku

 

The aim of the game is to fill in the missing numbers 1 to 9 in the pre-defined pre-filled table. This table is divided into 9x9 squares which are grouped into 9 squares (3x3). Additional numbers must be added to the pre-filled numbers so that all numbers one through nine are used in each row, in each column and in each of the nine squares. The order of the numbers is not important. The numbers must not be repeated in any column, row or small square.

At first glance, the solution seems easy, but the opposite is true. The difficulty of Sudoku is not determined by the number of hidden squares, but by their interconnections, which are not visible at first glance. Difficult Sudoku can take the average experienced solver around 15 ? 60 minutes.