The game starts with a 9 × 9 grid, some of which squares are filled in with numbers. The player must fill the missing digits with logic and complete the grid. One should remember that
- Any row should not contain more than one of the same numbers from 1-9.
- Any column should not contain more than the same numbers from 1-9.
- Any 3 × 3 grid should not contain more than the same numbers from 1-9.