Killer Sudoku keeps the familiar 9×9 Sudoku School board and controls, but removes the usual givens and replaces them with cages, target sums, and tighter arithmetic logic.
If you already enjoy classic Sudoku and want a more analytical variant without learning a completely different interface, this is a clean way to practice cage sums, combinations, and elimination on the original board.
The row, column, and 3×3 box rules still apply. The extra rule is that each cage has a target sum, and digits inside that cage must add up correctly without repeating.
Each cell must satisfy four layers of logic at once: row, column, 3×3 box, and cage. Unlike classic Sudoku, a cage can cut across box boundaries, so local arithmetic matters just as much as standard placement rules.
The colored cage regions and dashed outlines help you read the puzzle structure quickly. They are not decorative only — they show exactly which cells must share a target sum.
A digit can look legal by row, column, and box, but still be wrong because it repeats inside a cage or forces the cage sum to fail. On this page, cage-related conflicts are surfaced directly on the board.
You can still use reset, import, export, and solver mode. The difference is that good Killer Sudoku play depends on combining standard Sudoku elimination with cage totals and small-sum combinations.
Killer Sudoku keeps the familiar 9×9 rhythm of classic Sudoku, but adds arithmetic pressure through cages. The cleanest way to improve is to use cage totals as extra information instead of treating them as decoration.
New to Killer Sudoku? Read the complete Killer Sudoku rules guide for cage-sum basics and beginner strategies. For experienced players, our advanced Killer Sudoku techniques cover the 45 rule, innies/outies, and cage-splitting methods.