How to Play German Whispers

Standard Sudoku rules apply: fill every row, column, and 3×3 box with the digits 1–9, each appearing exactly once.

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.