How do you play Sudoku?+
Select an empty cell and enter a digit 1-9 so that no row, column, or 3×3 box repeats a number. Use the given clues to deduce the rest. You win when the whole grid is filled correctly.
What are the rules of Sudoku?+
Each of the nine rows, nine columns, and nine 3×3 boxes must contain the digits 1 through 9 exactly once. The puzzle starts with some cells pre-filled as clues, and you complete the remaining empty cells under those constraints.
How does the scoring work in this Sudoku?+
Your score is based on how quickly you solve the puzzle and how few mistakes you make. A fast, flawless finish scores highest. Your best result is saved locally so you can chase a personal record.
What happens when I make a mistake?+
A wrong placement costs one of your three lives and the cell is cleared so you can try again. Make three mistakes and the run ends in a game over.
How do notes work?+
Notes let you pencil in small candidate digits inside a cell without committing to them. They are perfect for tracking possibilities while you reason through the harder parts of the grid.
Is the puzzle always solvable?+
Yes. Every board is generated from a complete, valid solution and then reduced, keeping a unique logically deducible answer. You never face a puzzle with no correct completion.
Can I play Sudoku on mobile?+
Absolutely. The board and keypad are fully responsive and touch-optimized. Tap a cell, then tap a digit, exactly as you would with a mouse on desktop.
What is the best Sudoku strategy for beginners?+
Start with the easiest singles: look for rows, columns, or boxes missing only one digit. Fill those, then use the constraints they create to solve neighboring regions step by step.
What is the hidden singles technique?+
A hidden single is a digit that can go in only one cell within a row, column, or box even though that cell has other candidates. Spotting hidden singles is one of the fastest ways to make progress.
How is this different from classic paper Sudoku?+
The board auto-highlights related cells and duplicate numbers, and it tracks lives, timer, and score for you. The logic is identical, but the digital version removes bookkeeping so you can focus on solving.
Does my best score save between visits?+
Yes. Your highest score is stored in your browser's local storage, so it persists when you return. Clearing your browser data resets it, since the score lives on your device rather than a server.
Is there a time limit?+
There is no hard timer that fails you, but a faster finish earns a higher score. You can play at a relaxed pace and still complete the puzzle; speed simply boosts your rating.
How many difficulty levels are there?+
Each new game produces a fresh puzzle with a different clue layout. Because scoring rewards speed and accuracy, every board becomes its own challenge to beat.
Can I undo a move?+
Use the Erase control to clear the selected cell at any time. You can also re-select a filled cell and overwrite it with a new value, so correcting your work is quick and easy.
Are the clues generated or hand-made?+
They are generated procedurally from a fully solved grid, then reduced while preserving a unique solution. This guarantees a fair, always-solvable puzzle every time you start a new game.
Is Sudoku good for your brain?+
Yes. Sudoku exercises logical reasoning, concentration, and working memory. Regular short sessions can sharpen focus and provide a relaxing mental workout without time pressure.
Why do some cells highlight when I type?+
The board shows the active cell's row, column, and 3×3 box, plus every matching digit, so you can immediately see conflicts and plan placements. It is a visual aid, not a hint answer.
Is this Sudoku free to play?+
Yes. It runs entirely in your browser with no account, no download, and no cost. Open the page and start solving right away.
