In the well-known game of Sudoku, the player must complete a square grid of 9x9 numbers between 1 and 9, divided into nine 3x3 sub-grids, in which, at the beginning of the game, some of the cells (from a minimum of 20 to a maximum of 35 ) contain predetermined digits, so that each digit appears only once in each row, in each column and in each sub-grid.

In this version of the game, the player can choose the number of fixed cells, and then start a new game in which he has to fill the empty cells.

The game is facilitated by the fact that, if the player tries to enter into a cell a number clearly inconsistent with the context, the input is ineffective.

Beginners or impatient players can take a peek at the solution by clicking the `solution`

button,
which is however useful, at the end of the game, to control their own solution.

last revision: 01/08/2016