Logic Masters Deutschland e.V.

This idea for this puzzle was inspired by Billybeth's excellent puzzle I See No Dots, which left me wondering whether a German Whisper puzzle could be disambiguated by a single negative constraint.

I have set several puzzles with German Whisper clues which are disambiguated by a single clue: I have tended to use black dots for the purpose. This puzzle has a single German Whisper line, with no black dots given and a negative constraint on black dots. No adjacent pair of digits has one digit twice the other.

Opinions on difficulty have varied somewhat amongst testers. I have started it at 4/5, but a few solvers are likely to find it rather easier. The title arose because a tester who commented on the puzzle when it was called "What on earth is that" said that it was easy to forget a negative constraint.

Normal Sudoku rules apply.

On a green line adjacent digits must differ by at least 5 (standard German whisper)

Where digits are separated by a black dot, one is twice the other. All black dots are given.

Play in SudokuPad: The Antidot