Dots Sudoku

Kropki (Dots) sudoku rules

The player needs to fill all empty cells with numbers from 1 to 9. All numbers must comply with the following conditions:

• Unique digits in all rows;
• No digit repetition in all columns;
• Additional 3 by 3 squares cannot have duplicate digits;
• A white dot between cells indicates that the numbers in these cells differ by one (for example, 8 and 9, or 5 and 6);
• A black dot between cells indicates that the values in these cells are either more or less than each other by a factor of 2.

The game field consists of 9 rows, 9 columns, and 9 blocks of 3 by 3. A total of 81 cells. Some cells may have white or black dots between them, imposing certain restrictions on the numbers that can be in adjacent cells.

Kropki sudoku tips

Solving such a sudoku doesn't pose significant challenges, and the dots add interest to the game. Below are a couple of techniques that will help find the solution to this puzzle:

1. If a black or white dot is placed between two cells and one of the cells has the value 1, then the second cell must contain the number 2.
2. If a white dot separates two adjacent cells and one of them has the digit 9, then the other one must be 8.
3. If a black dot separates two cells, then these cells can only have the following values: 1 and 2, 2 and 4, 3 and 6, 4 and 8. This rule significantly narrows down the candidates.
4. Start filling cells that have at least one dot of any color nearby.
5. Use standard sudoku techniques.