Killer Sudoku

Sudoku with summed cages

Offline

Practice on your own, no connection needed.

Difficulty
Mistake check

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How to play

Killer Sudoku gameplay screenshot
  • Fill every row, column and 3×3 box with 1–9, once each. The dashed outlines are cages: the digits in a cage add up to the small number in its top-left corner, and no digit repeats within a cage.
  • Puzzles start with few or no digits, so begin with the cage sums: a 2-cell cage of 3 must be 1 and 2, and a 2-cell cage of 17 must be 8 and 9. Every puzzle has one solution and can be solved by logic alone, with no guessing.
  • When you select a cell, the bar above the number pad lists every digit combination for its cage and crosses out the ones the digits already on the board rule out.
  • In "Show mistakes" mode a wrong digit is not entered; it counts as a mistake and adds 20 seconds. "Free mode" doesn't check anything: clashing digits turn red, and the puzzle is done once every cell is right. A hint fills one correct cell and adds 30 seconds. This device keeps your solved count and best time for each difficulty.

Playing guide

These options and rules describe the current JoyPip version. Choose a mode above before starting; rules are also available during play.

Step-by-step examples

Select a step to see what changes. These are partial examples, not full starting positions.

Practice options

Difficulty
Easy · Normal · Hard · Expert
Mistake check
Show mistakes · Free mode

Detailed rules and controls

Controls
  • Tap a cell, then use the number pad or keys 1–9 to fill it; Delete/Backspace erases and the arrow keys move.
  • Note mode (N) records candidates; on a computer, Shift + a digit also adds a note. When you place a digit, it is removed from the notes in the same row, column, box and cage.
  • Undo (U) reverts the last fill, erase or note but never removes mistakes or hints; Hint (H) fills the selected cell first.
Solving basics
  • Cages with only one combination: 2 cells 3 = 1+2, 4 = 1+3, 16 = 7+9, 17 = 8+9; 3 cells 6 = 1+2+3, 7 = 1+2+4, 23 = 6+8+9, 24 = 7+8+9.
  • Rule of 45: every row, column and box adds up to 45. Subtract the cages that lie wholly inside it and you know the sum of the cells that poke in.
  • If a digit must appear in a cage and every cell of the cage that can hold it is in the same row (column, box), no other cell of that row (column, box) can hold it.
  • Expert puzzles have bigger cages and no given digits. Apply the rule of 45 to several adjacent rows or boxes (the cells poking in minus the cells poking out also make a fixed number), and check which combinations of the cages in one row (column, box) can hold together.

Frequently asked questions

When a cage has only one combination, how do you place each digit?

A 3-cell cage with a sum of 23 has only one combination: 6, 8 and 9. If the same row already has a 9 and only one cell of the cage lies outside that row, the 9 must go in that cell. Find cages with a single combination first, then use the rule of 45 for cells that poke in or out.

Do I need a download or a linked email?

Play directly in your browser without a download. Linking email is an optional way to recover your account. Before clearing browser data, consider whether you need to keep your account or local records.

Do matches earn or spend coins?

Earn coins by checking in and spend them on cosmetics. Matches never cost or award coins.

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