Hairpins
- Kropki dots
- Zipper lines
The brief
- Standard sudoku rules apply: The digits 1 through 9 appear in every row, column, and box.
- Zipper Line: Along Zipper lines, pairs of digits equidistant from the center of the line have the same sum.
- Kropki Pairs: Digits separated by a black dot are in a 1:2 ratio. Digits separated by a white dot are consecutive. Not all dots are necessarily given.