How Killer Sudoku works
Killer Sudoku follows every classic rule — the digits 1–9 once per row, column and 3×3 box — and adds cages: dashed outlines with a small number showing the sum of the digits inside. Digits cannot repeat within a cage.
Cage arithmetic is the way in: a two-cell cage summing to 3 can only be 1+2, and one summing to 17 can only be 8+9. Combine sums with classic elimination to crack the grid. Your progress, notes, streak and daily result are saved on this device.
New to the variant? Start with the beginner guide, sharpen up in the techniques hub, or switch back to Classic Sudoku or Windoku.