Zipper or Ziffer?
- XV and number dots
- Whisper lines
The brief
- Normal sudoku rules apply.
- GERMAN WHISPER LINES: Adjacent digits along a green line must have a difference of at least 5.
- Digits separated by an X sum to 10.
- For each purple line it must be determined whether it's a Zipper line or a Ziffer line.
- ZIPPER LINES: Each pair of digits an equal distance from the central spot on a Zipper line have the same SUM, which appears on that central spot.
- ZIFFER LINES: Each pair of digits an equal distance from the central spot on a Ziffer line have the same DIFFERENCE, which appears on that central spot.