Killer Sudoku is Sudoku with a twist: instead of starting digits, the grid is split into dashed cages, each with a small sum. Fill the grid so every row, column and box has 1 to 9, and every cage adds up to its number.
The rules
Every row, every column and every 3×3 box contains the numbers 1 to 9 exactly once.
Each dashed outline is a cage. The small number in its top-left corner is the total of the numbers inside it.
A number can’t repeat inside a cage, so a 2-square cage adding to 4 must be 1 and 3, never 2 and 2.
Every puzzle has exactly one solution, and you can reach it by logic alone.
Playing in Everyday Games
Tap a square, then a number to place it. Tap the same number again to clear it.
The selected square’s row, column, box and cage are shaded, and its cage outline lights up.
The cage helper under the board shows the cage’s sum, how much is left, and the sets of numbers that could still make it. Tap the eye to hide the sets for a purer challenge.
Notes pencil in candidates. Placing a number clears it from the notes in its row, column, box and cage.
A repeated number turns red, and a cage sum turns red when its numbers go over or don’t match once the cage is full. Hint fills in one square; Undo takes back a move.
Combinations worth knowing
Some sums can only be made one way. In two squares, 3 is always 1+2, 4 is 1+3, 16 is 7+9 and 17 is 8+9. In three squares, 6 is always 1+2+3 and 24 is 7+8+9. Start with these cages: they pin down numbers quickly and give you a foothold.
The 45 rule
Every row, column and box adds up to 45 (1+2+…+9). If the cages lying completely inside a box cover all but one square, that square must be 45 minus their total. If a cage sticks out of a box by one square, that square is the cage totals minus 45. The same works across two or three rows or columns (90 and 135), and it is the key technique on Hard and Expert.
Difficulty levels
Easy: small cages and a few numbers already placed. Cage combinations and singles are enough.
Normal: an empty grid with cages of up to 4 squares. You’ll use the 45 rule on single rows, columns and boxes.
Hard: bigger cages, up to 5 squares.
Expert: the biggest cages, up to 6 squares. Expect to apply the 45 rule across several rows or columns.
Best times are kept separately for each difficulty.