Sudoku is very entertaining logic puzzle. It became popular in the early 00's and since then is still a good game for all ages and skills. The objective is to fill a 9×9 grid with digits from 1 to 9 following some simple rules.

- Select an empty cell and choose a number from 1 to 9 to fill it;
- The objective is to fill all the cells following these three basic rules:
- Don't repeat the numbers in the same
**row**; - Don't repeat the numbers in the same
**column**; - Don't repeat the numbers in the same
**subgrid (3x3 box)**;

- Don't repeat the numbers in the same