Sudoku Classic: Tidoku

Tidoku is a classic sudoku game that teaches you to solve, offline. Learn sudoku by logic: every sudoku has one solution and solves with no trial and error, no guessing. Find a Naked Pair, an X-Wing or a Swordfish yourself and Tidoku names the technique. Classic sudoku, Killer Sudoku, Jigsaw and Diagonal, a daily sudoku and a 600-level Journey.

Learn sudoku techniques
The Tide Chart lists 31 sudoku techniques, from Naked Single and Hidden Single up to Skyscraper, XYZ-Wing, W-Wing, Swordfish and Jellyfish, plus the Rule of 45 for Killer. Each technique has a one-minute sudoku tutorial, and most have practice puzzles built to need it. It is calm sudoku, one technique at a time.

Sudoku hints that name the technique
Nudge shows where to look and never costs a coin. Explain names the technique, walks you through it step by step with colour-coded words, and lights the cells that prove it: no cost on Easy, Medium or in lessons, three a day from Hard up, then coins. Place writes the digit. A hint never just says "try and see", even on Extreme. These sudoku hints teach, so you stop needing them.

Spotted: sudoku that sees how you solve
• Place a digit no single could give you, with no hint open, and Tidoku names the technique you just used: Spotted! A glass bell rings and a short voice line in English cheers.
• Spot a technique on three different puzzles and its lighthouse lights on your Tide Chart: mastered.

Sudoku for beginners, and for experts
• Six tiers, from Easy, Medium and Hard to Expert, Master and Extreme. Easy sudoku boards and one-minute lessons make Tidoku friendly sudoku for beginners.
• Every sudoku is solved by logic, never by trial and error, even on Extreme.
• Classic sudoku, Killer, Jigsaw sudoku and Diagonal sudoku boards.
• A Journey of 600 levels in 30 chapters brings in the techniques one by one.

Killer Sudoku that is easier to read
Tinted cages, a cage helper that lists the digit sets for each sum, and the Rule of 45 taught like any other technique. Easy and Medium Killer sudoku boards give more digits; harder ones give few or none.

Daily sudoku with a weekly rhythm
• The Daily Puzzle is the same sudoku for everyone: Easy on Monday, rising to Master on Saturday, Killer on Sunday. Past days wait in the calendar, and a full month wins a trophy.
• The Weekly Challenge: one hard sudoku a week. Solve it in Classic or Strict with no hints and your time goes on the Play Games leaderboard.

Festival events
Festival of Lights, 1 to 10 November 2026: ten Diwali sudoku puzzles. Solve all ten and the Diya Lights look is yours to keep. At other festivals, Restore the harbour adds a picture piece with each win.

Mistakes your way
Classic allows three mistakes, Relaxed has no limit and hides wrong digits until you tap Check, and Strict stops at the first. A quick mis-tap is forgiven within three seconds, once per puzzle.

Calm sudoku, easy to read
• Dark mode: Charcoal and Night Tide. Classic: a white board with black digits and one blue for yours. Paper Tide, Sea Glass and Harbour are there too.
• Big digits, three text sizes, a left-hand layout, a timer you can hide and screen-reader labels. Play in portrait or landscape.
• Musical digits: each digit plays its own note, and a finished row, column or box plays its own tune.

Everything a sudoku player needs
Pencil notes in three Notes modes, Undo and Redo, Erase, Restart and a Pause that hides the board. Matching digits light up and conflicts are marked. Colour marks tint cells in four shades.

Coins and Play Games
Coins come from solving the Daily, the Weekly, Stretch puzzles and every technique you master. Spend them on Explain hints or one more chance in Classic. Google Play Games adds achievements and cloud save.

Sudoku offline
Every sudoku plays offline: the Journey, the Daily Puzzle and the Weekly Challenge come inside the game. 13 languages. Coin packs are optional.

Sudoku classic, number puzzles and logic puzzles in one calm app: learn sudoku as you play.

Recent changes:
New: a sliding row on the home screen shows our other puzzle games. Tap one to see it on Google Play. Plus small fixes.