How to play Sudoku

Sudoku is a logic puzzle played on a 9×9 grid divided into nine 3×3 boxes. Some cells are already filled in; your job is to fill in the rest. No maths is needed — only logic.

The rules

1. Each row must contain the digits 1–9 exactly once.
2. Each column must contain the digits 1–9 exactly once.
3. Each 3×3 box must contain the digits 1–9 exactly once.
4. The given digits cannot be changed. Every puzzle has exactly one solution.

Controls

• Tap a cell, then tap a number. On a keyboard, use the arrow keys and 1–9.
• Turn on Notes (or press N) to pencil in possible candidates.
• Undo (Ctrl+Z) takes back your last move; Erase (Backspace) clears a cell.
• Wrong digits are shown in red and count as a mistake.

Tips and strategies

• Single candidate: if only one digit fits in a cell, place it.
• Hidden single: if a digit can go in only one cell of a row, column or box, it belongs there.
• Scan by digit: pick a digit and check every box for where it can go.
• Use notes on harder puzzles and clear them as you place digits.
• Naked pairs: two cells in a unit with the same two candidates remove those digits from the rest of the unit.

Scoring

Each level has a base score (easy 100, medium 250, hard 500). Solve faster than the target time for up to double points; each mistake costs 10%. Daily puzzles add a streak bonus of +10% for every consecutive day you visit, up to +100%.

Frequently asked questions

Start playing →