Alphadoku: Letter Sudoku

Contains adsIn-app purchases
Content rating
Everyone
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Content rating
Everyone
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About this game

Nine letters. One hidden line.

Alphadoku brings a new deduction to Sudoku. Fill every row, column, and 3×3 box with the nine letters of a target word or phrase. Each letter appears once in every row, column, and box.

The twist? Exactly one row or column spells the target in order. The phrase is visible from the start. Your challenge is to discover where it belongs.

FOLLOW THE CLUES
Compare the board with the numbered target. Cross off impossible lines, narrow your shortlist, and confirm your answer. In Medium, the whole phrase falls into place. Hard and Pro leave every remaining letter for you to fill.

CHOOSE YOUR CHALLENGE
Start with Easy, where the hidden line is shown. Try Medium to learn the hunt, then take on Hard with Expert Deduction: confirm the hidden line and fill it yourself. Pro adds an unassisted challenge with fewer starting letters and no revealing hints.

THINK IT THROUGH
Use pencil marks to track possibilities. Undo a move, erase an entry, or reveal a letter with a hint on Easy, Medium and Hard. Matching-letter highlights and remaining-letter counts help you read the board.

LEARN AS YOU PLAY
Learn through a short interactive practice puzzle, then replay it whenever you like. Open How to play from Home or during a puzzle for every control. Full-size row, column and hidden-line selectors provide an alternative to the grid headers.

PICK UP WHERE YOU LEFT OFF
Your current puzzle saves on this device, including pencil marks and undo history. Choose Continue on Home to resume.

Finish the grid to see your active time, mistakes and hints used. Play again starts another puzzle at the same tier, or return Home to change your challenge.

Every letter has a place. Can you find it?
Solve letter Sudoku. Find the one hidden line. Play from Easy to Pro.
Updated on
Oct 2, 2026
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Data safety

Safety starts with understanding how developers collect and share your data. Data privacy and security practices may vary based on your use, region, and age. The developer provided this information and may update it over time.
  • This app may share these data types with third parties
    Location, Personal info and 3 others
  • This app may collect these data types
    Location, Personal info and 3 others
  • Data isn’t encrypted

What’s new

Meet Alphadoku: letter Sudoku with one hidden line. Choose Easy, Medium, Hard or Pro, and solve with pencil marks, undo, erase and hints.