Killer Sudoku and classic sudoku with no ads, ever. Solve a daily killer sudoku or a classic daily challenge, train your brain with calm logic, and play it all offline: on the subway, on a plane, anywhere.

WHY QUIETDOKU
✓ No ads, ever: not between games, not for hints, not anywhere.
✓ Hints appear only when you tap — the app never plays for you.
✓ Cage combinations are off by default, so the thinking stays yours. Turn them on in settings whenever you want a helper.
✓ Fully offline, Killer included: every puzzle is on your phone. No third-party analytics or tracking.

WHAT IS KILLER SUDOKU?
Killer Sudoku, also known as sum sudoku, sumdoku or cage sudoku, is sudoku plus a little addition. Dashed boxes called cages have a small number in the corner: the sum of the digits inside. Follow the usual sudoku rules and make every cage add up.

HOW TO PLAY KILLER SUDOKU
✓ Like classic sudoku: fill every row, column and 3×3 box with 1–9, no repeats.
✓ The digits in a cage add up to the number in its corner.
✓ No digit repeats inside a cage.
✓ Tip: every row, column and box adds up to 45.
✓ Tap ? at the top any time for the rules and three starter tricks.

PUZZLES
✓ Classic: Easy, Medium, Hard and Expert — 12,000 puzzles.
✓ Killer: Easy, Medium, Hard, Expert and Extreme — 13,000 puzzles. Easy to Hard start with a few given digits. Expert and Extreme give you no numbers at all, only the cages and their sums.
✓ Every puzzle has exactly one solution. Pure logic, no guessing.

DAILY CHALLENGES & LEADERBOARDS
✓ 9 daily challenges: 5 daily Killer puzzles, one for each level, plus 4 classic. Pick your level.
✓ Everyone in the world gets the same puzzles, with a leaderboard for every level.
✓ A monthly calendar lights up as you solve, with a trophy for a full month. Miss a single day and your streak is still safe.

TOOLS THAT HELP
✓ Stuck? Tap a hint and the next logical cell fills in; in Killer, one sentence explains why, so every hint doubles as a lesson. 1 hint per game (3 with Pro).
✓ Optional cage helper: select a cell and see every digit combination that fits its cage sum.
✓ Notes, unlimited undo, erase and matching-number highlights.
✓ By default nothing turns red while you play — wrong cells are shown once the grid is full. Pro can turn on mistake alerts.

LEVELS, RANKS AND ACHIEVEMENTS
✓ Every solve earns XP. Your level only goes up, with a new title every 10 levels — from Apprentice to Legend.
✓ Online, your rating sets your rank from Bronze to Grandmaster, with daily, season, country and friends leaderboards.
✓ Streaks, personal bests, your first Expert solve and your first Killer Extreme solve become achievement cards to save or share.
✓ Send a friend a link to the same puzzle and compare times.

QUIETDOKU PRO (OPTIONAL)
• Free for everyone, forever: all 9 daily challenges, leaderboards, achievements, hints and cloud sync — and no ads, for anyone.
• Free play: 3 practice puzzles a day (Classic and Killer combined). Pro unlocks unlimited practice at every level.
• 3 hints per puzzle instead of 1, optional mistake alerts (wrong entries turn red right away; the 4th mistake ends the game), plus Pro-only avatars and a PRO badge.
• Print classic puzzles as a PDF: pick a level, 1, 2, 4 or 6 per page, with an optional answer page. Made on your phone, no internet needed.
• Choose monthly, yearly (with a 7-day free trial) or a one-time lifetime purchase. Prices are shown in the app in your local currency.
• Subscriptions renew automatically unless cancelled at least 24 hours before the end of the current period. Payment is charged to your Google Play account; manage or cancel anytime in your account settings. Any unused part of a free trial is forfeited when you buy a subscription.
Privacy Policy: https://quietdoku.com/privacy

No sign-up needed. Rankings use an anonymous ID — no email, no phone number. Optionally sign in with Apple or Google to keep your progress when you switch phones.

Just sudoku. No ads, ever.