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Fill the 9×9 grid so that every row, column, and 3×3 box contains the digits 1–9 exactly once. Tap an empty cell to select it, then tap a number from the panel to fill it in. Use pencil mode to jot down candidate numbers without committing to an answer.

One Sudoku offers four levels: Easy, Medium, Hard, and Expert. Easy puzzles have more given numbers and are great for beginners. Expert puzzles require advanced techniques and are suited for experienced solvers.

Tap the pencil icon in the toolbar to toggle notes mode. In notes mode, tapping a number adds it as a small candidate note inside the cell without committing it as a final answer. Toggle back to normal mode to enter final answers.

Tap the undo button (↩) in the toolbar to step back one move at a time. You can undo as many times as you like.

A fresh puzzle is available every day — the same puzzle for every player worldwide. Completing it extends your daily streak. Miss a day and your streak resets.

Your game data is stored locally on your device. If you have iCloud Backup enabled in iOS Settings, your data is included in your backup and will be restored when you reinstall the app or switch to a new device.

One Sudoku is only available in English.

Go to Settings (gear icon) inside the app and tap "Reset All Progress". This clears all statistics, streaks, and completed puzzles. This action cannot be undone.

Yes. Puzzles are generated on-device, so you can play anywhere without an internet connection.

Yes, One Sudoku shows small banner ads at the bottom of the screen to keep the app free. You may also see a short ad after completing a puzzle. Additionally, you can choose to watch a video ad to earn extra hints — this is entirely optional.