How to Play Jigsaw Sudoku

The rules

Playing the game

• Tap a cell, then a number to place it. Tap the same number again to clear it.
• The dark numbers are clues and can’t be changed.
• The selected cell’s row, column and region are shaded, and matching numbers light up.
• Each number key shows how many of that number are left to place.
• On a keyboard: 1–9, arrow keys, Backspace, N for notes, H for a hint and Ctrl or ⌘+Z to undo.

Notes, hints and conflicts

• Turn on Notes to pencil in candidates. Placing a number removes it from the notes in the same row, column and region.
• A number that repeats in a row, column or region turns red, along with the number it clashes with.
• Hint fills in the selected cell, or the next one that needs it. Hints are counted.
• Undo takes back any change.

Strategy for irregular regions

• Trace each region’s shape before you start. Long, thin regions that cross many rows or columns are full of clues.
• Look for a digit that can only go in one cell of a region, the same way you would in a box.
• If a region sits almost entirely in one row, the cells left over tell you which digits the rest of that row must hold.
• Use notes on Hard: candidate pairs inside a region often unlock the next step.

Difficulty levels

• Easy: 36 clues, and every step is a cell with only one possible number.
• Normal: 30 clues. Sometimes a number has only one place left in a row, column or region.
• Hard: 24 clues, and singles alone won’t finish it.
• Best times are kept separately for each difficulty.

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