Sudoku

Sudoku is a number puzzle played on a 9×9 grid. Fill every empty cell with a digit from 1 to 9 so that each row, column and outlined 3×3 box contains every digit exactly once. No arithmetic is required: you solve the puzzle by ruling out impossible positions. The starting clues are fixed and cannot be erased.

How to play Sudoku

Choose a difficulty and select Start game. If you have an unfinished puzzle, select Continue game. Click or tap an empty cell, then choose a digit from the keypad. The highlighted row, column and box help you follow the selected cell; matching digits make the board easier to scan.

Begin with a nearly complete row or box. Identify the missing digits and compare each empty cell with its crossing column. Enter a number when only one candidate fits. After every placement, check the surrounding areas again: a single discovery can reveal several more.

Four difficulties

Choose Easy, Medium, Hard or Expert. Easier puzzles offer more direct eliminations and single candidates. Harder puzzles call for closer comparisons between candidates across rows, columns and boxes. Every prepared puzzle is checked for a unique solution.

The timer records your solving time without imposing a deadline. Pause hides the board and stops your personal game. Incorrect entries are highlighted and counted, but three mistakes do not end the puzzle. Correct the entry or undo your move and continue at your own pace.

Notes and helpful explanations

Turn on Notes to record small candidate digits in an empty cell. Enter the same candidate again to remove it. When you know the answer, turn Notes off and place a normal digit. Correct placements also update related notes.

Undo reverses the previous change, while Erase clears the selected editable cell. Hint explains a logical step, such as why a digit has only one possible position or which candidates can be eliminated. Hints remain counted even if you undo the resulting move.

Daily puzzles and progress

Enable Daily puzzle before starting. The same date and difficulty produce the same puzzle; the date changes at midnight UTC. Return to a random puzzle through the new-game menu.

Guest progress is saved on the current device. Signing in loads your account's separate progress. Check the save status and use Retry if a save fails. The shared invitation button lets accepted friends work on one grid together. Coloured markers show their selected cells. Visiting a friend's board does not replace your own unfinished puzzle, and cooperative or assisted solutions are kept separate from unassisted solo best times.

Print Sudoku

Select Print Sudoku to choose a clean puzzle or your current entries, A4 or US Letter paper, and one, two or four puzzles per sheet. The current puzzle comes first; extra puzzles use the same difficulty. You can add solutions on a separate page. Notes and game controls are omitted from the printout, and preparing printable puzzles never changes your active game.

Tips

• Check the row, column and box together before placing a digit.
• Look for areas with only two or three empty cells first.
• Use notes when immediate placements run out; keep guesses separate from confirmed answers.
• Read the hint explanation and try the same technique elsewhere.
• Take a break when the board stops making sense. There is no countdown.

Similar games

Hexa Crown also rewards planning around the space available on the board. For a different kind of tactical planning, try Kingdom Defense 3D, choosing and developing defensive towers. Find more number and logic challenges in Puzzle games.