Spike
by FullDeck and Missing a Few Cards Open on SudokuPad
Heartburn
- 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. For Zipper lines of odd length, that sum is the central digit on the line. - Kropki pairs: Digits in cells separated by a black dot are in a 2:1 ratio. Digits in cells separated by a white dot are consecutive. Not all dots are necessarily given.