Sudoku: One Unique Solution

Sudoku with a unique solution is a quiet number puzzle without registration. Play offline, choose a level and continue your saved game. The generator builds a valid 9×9 grid and checks uniqueness after removing clue pairs. Four levels target about 40, 34, 30 and 25 given cells. A few extra clues may remain to preserve uniqueness. Levels describe clue counts rather than a calibrated rating of solving techniques. Select a cell and a digit. Repeating the digit removes it. Pencil mode stores up to nine candidates, erase clears a cell, and undo restores values and notes without refunding elapsed time or hints. Highlight rows, columns, boxes and matching numbers. Optional duplicate highlighting shows conflicts; Check grid compares filled cells with the unique solution. Each game starts with three hints. With advertising disabled in this package, extra hints and grid checks are free. Banners and interstitials never cover the playing board. The timer measures active play. Pausing or leaving the foreground hides the board and requires an explicit resume. One game per level plus a separate daily game is saved locally, including notes and undo history. View completed games, best and average times and a daily streak. The daily puzzle uses your local calendar date and the same algorithm version across devices. Russian and English, light and dark themes. No account or cloud sync is required.