aigcgamePLAY LAB
← SUDOKU COLLECTION
BRICK / VARIANT

Kropki Sudoku

White dots join consecutive digits, black dots join doubles.

Click a cell, then a digit. Arrow keys move, 1–9 place, Backspace clears.

Rules

A white dot between two cells means those digits are consecutive — 3 and 4, or 8 and 9. A black dot means one is exactly double the other — 2 and 4, or 3 and 6. Cells with no dot are unconstrained in this version.

  • White dot: the two digits differ by exactly 1.
  • Black dot: one digit is double the other.
  • Digits not joined by a dot have no relation.
  • Doubles are only possible for 1-2, 2-4, 3-6 and 4-8 — a black dot rules out 5, 7 and 9.

Good to know

Ordinary sudoku rules still apply underneath the variant: every row, column and 3×3 box holds 1–9 exactly once. The extra rule sits on top and is usually what breaks the puzzle open.

More sudoku

All sudoku variants ↗

Or read how to play Sudoku ↗.