How to play Killer Sudoku
Killer Sudoku keeps the three classic rules (each row, column and 3×3 box holds 1–9 once) and adds cages: groups of cells outlined with dashes, with a total in the corner. The digits in a cage must add up to that total, and no digit may repeat within a cage.
Start with the cages that have only one answer
A two-cell cage totalling 3 can only be 1+2. A two-cell 17 can only be 8+9. A three-cell 6 is always 1+2+3, and a three-cell 24 is always 7+8+9. Pencil those in first; they anchor everything else. The full list lives on the cage combinations chart, which also filters combinations by digits you have ruled in or out.
Then use the rule of 45
The digits 1–9 add up to 45, so every row, column and box totals 45. Add the cages lying fully inside a box; whatever is missing from 45 belongs to the remaining cells. When a single cell is left over, you have just found its value without guessing.
Why Killer feels different
Classic Sudoku is pure placement logic. Killer adds small sums, so you are trading between two kinds of reasoning: which digits a cage allows, and where those digits can sit. Most players find the first few minutes slower and the finish faster, because once a few cages resolve, the rest of the grid falls quickly.
Ask the puzzle coach
Stuck on a rule or a tactic? Ask in plain words. The coach only talks puzzles, and the answer is written for you on the spot.
Questions players ask
How do you play Killer Sudoku?
Normal Sudoku rules apply: 1–9 once in every row, column and 3×3 box. On top of that, the dashed cages show a sum, and the digits inside a cage must add up to it without repeating.
Can a digit repeat inside a cage?
No. A cage never contains the same digit twice, even if the cage spans two boxes.
What is the rule of 45?
Every row, column and box adds up to 45 (1+2+…+9). If the cages covering a box add up to 45 plus a bit that sticks out, the cells that stick out must sum to that bit. It is the main tool for cracking Killer puzzles.
Why do some puzzles show starting digits?
Easy and Medium Killer puzzles place a few digits to get you going. Hard and Expert rely on the cages alone except where one digit is needed to keep the solution unique.
What is the cage helper?
Select any cell and the panel lists every set of digits that can fill its cage. Combinations that clash with digits you have already placed are struck through.