German Whispers
Adjacent digits on the green line must differ by at least 5
German Whispers is fully playable. Choose a difficulty and start solving.
German Whispers (also known as Whisper Sudoku) draws green lines on the grid. Any two digits that are adjacent on the line must differ by at least 5. Because the minimum difference is 5 and digits range from 1–9, this creates a strong alternating high-low pattern: if one cell is low (1–4), the next must be high (6–9) and vice versa. The line constraint eliminates 5 as a valid digit in most positions.
Like all Sudoku variants, German Whispers builds on the classic 9×9 foundation. Every row, column, and 3×3 box must contain each digit from 1 to 9 exactly once. The variant constraint is added on top of these standard rules, never replacing them.
If you're new to Sudoku, start by learning the basic rules and techniques before attempting variants.
Techniques Useful for This Variant
| Technique | How it applies |
|---|---|
| Pencil Marks / Notes | Essential for tracking candidates alongside the variant constraint |
| Obvious Singles | Cells narrowed to one candidate by the combined constraints |
| Hidden Singles | Digits with only one valid cell in a unit after variant elimination |
| Pairs and Triples | Locked candidates exposed by the additional constraint |