How to play

Row, column and box – each holds the digits 1 to 9 exactly once.

In Killer Sudoku the digits in a dotted cage add up to the sum in its corner.

Sudoku

A 9×9 grid. Every row, every column and every 3×3 box must hold the digits 1 to 9 exactly once.

Killer Sudoku

The same rules, plus dotted cages with a sum in the corner. The digits in a cage must add up to that sum, and no digit repeats inside a cage. A cage always has at least 2 cells. On Extra easy, Easy and Medium you start with 25, 15 and 5 digits filled in; Hard and Expert start empty.

Placing digits

Tap a cell, then tap a digit. The number buttons show how many of each digit are left. Correct digits lock and can't be changed, and a wrong digit never stays on the board.

Hints – 2 per game

A hint fills in the correct digit in the empty cell you have selected. If you aren't on an empty cell, nothing happens and the hint isn't used. A hint doesn't explain why – that's what How to solve and Techniques are for.

Mistakes – 2 allowed

A wrong digit flashes red and is counted («Mistakes 1/2»). The third mistake ends the game. You can then try the same board again or start a new one. Notes never count as mistakes.

Notes (pencil marks)

Turn on notes mode and tap digits to pencil in candidates. Notes are removed automatically when that digit is placed in the same row, column or box. Undo and Erase work on notes too.

Time and pause

The timer stops while the app is in the background. Pause hides the board.

One active game per game type and level

If you start a new board, the one you were on counts as abandoned.

Numbered boards

Everyone plays the same boards in the same order («Killer Sudoku · Medium · Board #17»). Only your first attempt at a board counts towards the shared numbers. You can replay any board from your history.

Clean solve

A board solved with no hints and no mistakes.

Statistics

Games completed, clean solves, win rate and best times per game type and level. After a board you see the average and median time, how many players finished it, and how many of them you were faster than (shown once enough players have solved it).

Weekly reminder (optional)

It only arrives if you haven't played for a week, and at most four times.