Killer Sudoku
Killer sudoku is sudoku with arithmetic woven in: the grid is carved into dashed cages, each cage must add up to the small number in its corner, and a digit may not repeat inside a cage. Most of the grid starts empty — the sums themselves are the clues, and the pleasure is in making them talk. Every puzzle here is generated fresh and verified to have exactly one solution before you see it.
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Killer Sudoku
Sudoku with cages that must add up — no starting numbers needed.
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Classic 9×9 sudoku — relaxed, with a hint that teaches.
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The hardest setting — grids stripped down to the bare minimum of given numbers.
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One fresh 9×9 puzzle a day — the same for everyone.
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Why play killer sudoku?
It works two muscles at once. Classic sudoku is pure elimination; killer adds mental arithmetic — every cage is a little sum puzzle, and the strongest moves come from reading several cages together. Because each row, column and box always totals 45, the sums quietly hand you information no single clue states outright. That mix of counting and deduction is a genuinely different workout from the classic grid.
And it meets you where you are. Gentle mode reveals a few starting digits so the first foothold is visible; the hint button teaches the next true step instead of just filling a square; conflicts are highlighted quietly rather than punished; and there is no game over, ever. The clock stays hidden unless you switch it on, large-print digits are one tap away, and an unfinished grid is saved on your own device.
Frequently asked questions
Is killer sudoku free to play?
Yes. Killer sudoku here is free with no ads, no download and no account. Your puzzle and your settings stay on your own device.
How do you play killer sudoku?
All the classic rules apply: every row, column and 3×3 box holds the digits 1–9 exactly once. On top of that, the grid is divided into dashed cages, and the digits in each cage must add up to the number printed in its corner — without repeating a digit inside the cage. Fill the whole grid so both sets of rules hold and the puzzle is solved.
How is killer sudoku different from regular sudoku?
A regular sudoku starts with given digits scattered around the grid; killer usually starts almost empty, and the cage totals carry the information instead. That trades some elimination work for arithmetic: you reason about what a cage summing to, say, 7 across three squares can contain (only 1, 2 and 4), and the givens you would normally lean on emerge from the sums.
What is the 45 rule?
Every row, column and 3×3 box contains 1 through 9, which always adds up to 45. So if the cages inside one box account for 40 and a single square pokes out, that square is a 5. Adding up the cages of a row, column or box and comparing against 45 is the single most useful killer technique, and most hard steps start there.
Can a digit repeat inside a cage?
No — a cage never repeats a digit, even when the row, column and box rules alone would allow it. That is what makes small sums so telling: a two-square cage totalling 3 must be 1 and 2, a three-square cage totalling 24 must be 7, 8 and 9.
Do these puzzles have a unique solution?
Yes. Every puzzle is generated fresh and then checked by a solver before it is shown to you: if the cages do not force exactly one solution, the board is thrown away and re-made. You will never meet a grid with two answers or none.
I am new to killer sudoku — any beginner tips?
Start in gentle mode, which reveals a handful of digits so the grid is not a blank wall. The most useful beginner strategy is to work the smallest and largest cage totals first — they allow the fewest combinations — and to keep candidates with the notes pencil. When you are stuck, the hint button does not just fill a square: it points at the easiest true step and tells you why it works.
Is there a timer?
Only if you want one. There is no countdown and no time limit — the clock stays hidden until you switch it on, and nothing about the game rushes you.
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