How to Play Sudoku

A standard sudoku puzzle uses a 9×9 grid made of nine rows, nine columns, and nine 3×3 blocks (also called boxes or regions). Some cells are filled in at the start; your job is to fill the rest.

Each empty cell must contain a single digit from 1 through 9. When the puzzle is complete, every cell holds one of these digits—no letters, symbols, or multiple numbers in one cell.

Each digit 1–9 must appear exactly once in:

• Every row — no repeats along any horizontal line;
• Every column — no repeats along any vertical line;
• Every 3×3 block — no repeats inside any of the nine outlined boxes.

If a digit already appears in a row, column, or block, you cannot place the same digit again in that row, column, or block. A valid puzzle has exactly one solution that satisfies all three rules.

You solve sudoku by logic and deduction: use the given numbers and the rules above to figure out which digit belongs in each empty cell. You should not need guessing; if you reach a point where you must guess, look for a deduction you missed or use pencil marks (candidates) to track possibilities.

Puzzles are rated by how many techniques are needed, not by rotation or theme. In Sudokitty you may have tools such as notes, hints, or undo—the core rules above stay the same. When in doubt, the in-game help or settings describe what each control does on your device.