What is Killer Sudoku?

Killer Sudoku combines Sudoku with simple arithmetic. It uses the normal 9×9 rules plus dotted "cages" of cells that must add up to a target sum.

What do the dotted cages and small numbers mean?

The dashed outline groups cells into a cage, and the small number in its corner is the total those cells must add up to.

Can a digit repeat inside a cage?

No. Besides the usual row, column and box rules, a digit cannot repeat within a single cage.

Does Killer Sudoku have starting numbers?

Usually not. Killer puzzles often start with an empty grid and are solved purely from the cage sums and Sudoku rules.

What is the 45 rule in Killer Sudoku?

Each row, column and 3×3 box always sums to 45 (1+2+…+9). Comparing that total to the cages that cover a region lets you deduce missing values.

💀 Killer Sudoku

Killer Sudoku combines Classic logic with light arithmetic. The standard rules still apply (1–9 in every row, column and box), but there are no given numbers.

Cages

The grid is split into dashed-outlined cages. Each cage shows a small target sum in its corner:

The digits inside a cage must add up to its target sum.
A digit can never repeat within a single cage.

Built-in helper

Select any cell and SudokuStreak highlights its whole cage and shows a live “Cage N — X to go” readout, so you always know the target and what’s missing.

Pro tip

Memorise forced combinations: a 2-cell cage summing to 3 can only be {1,2}; one summing to 17 can only be {8,9}.

🏆 Difficulties & scoring

This type can be played on all five difficulties. The score multiplier for Killer is ×1.3 — so every point counts for more on this variant. The "normal time" below is tuned for this type.

Difficulty	Base score	Max (×1.3)	Normal time	Hints
easy	150	390	7 min	6
medium	300	780	14 min	5
hard	600	1560	21 min	4
expert	1000	2600	28 min	3
evil	1500	3900	42 min	2

How the score is calculated

Your score builds up from 0 as you place correct numbers, up to the full base when the board is finished. Then two bonuses are added:

base × (1 + combo bonus + time bonus) × 1.3

Progress: the live score climbs from 0 to the base as the grid fills with correct numbers.
Combo bonus (up to +50%): keep a clean run for the full bonus. Each error or hint is a combo break that shrinks the bonus — but it never takes points away below the base.
Time bonus (up to +50%): beat the normal time and you earn extra, proportional to how much faster you were. Finishing slower than normal costs nothing — there is no time penalty.
The total is multiplied by ×1.3 and never drops below 0.

Coins

The coins you earn reflect your score — the more points, the more coins (about 1 coin per 20 points, minimum 1). Spend coins in the Shop on hints and Jokers.

Tip: a clean, hint-free solve under the normal time scores the highest. The Daily Challenge is always Classic and fully scored.