NineSquare: Sudoku

Why NineSquare

• Every puzzle is free and already yours. 19,200 puzzles come inside the app. Nothing to unlock, download or subscribe to.
• Levels you can trust. Each puzzle is graded by the solving techniques it needs, not by how many digits it starts with. Easy needs only the simplest steps; Expert asks for more than singles.
• Like pen and paper. The default style, Classic, shows no hints while you solve. Prefer a safety net? Switch to Relaxed, or pick your own helpers.
• Private by design. No account, no ads, no tracking. Your progress stays on your phone.

Features

Puzzles

• 19,200 puzzles: 4 levels × 12 books × 400 puzzles each.
• Puzzles come in Books (“Easy · Book 3”, puzzle “Book 3 · No. 17”), so you always know where you are and how far you’ve come.
• Tap a level on Home to play its next puzzle, or browse its books and filter puzzles by progress.
• Continue right where you left off. Unfinished puzzles keep their digits, notes and undo history.

Play your way

• Notes (pencil marks), Undo, Redo, Erase and Hint.
• Classic (paper): no hints while you solve, like pen and paper.
• Relaxed: shows clashes and wrong digits as you go.
• Custom: your own choice of helpers: clash display, instant mistake check, highlights, used-up digits, timer, and keeping the screen on.
• Each digit key shows how many of that digit are left to place.

Stats that motivate

• Solves, streaks and solve times, filtered by 7 days, 30 days or all time.
• A per-level table, an activity calendar of up to 52 weeks, and a solve-time chart for each level.

Your language, your digits

• The app speaks English, Hindi, Bengali, Marathi, Telugu, Tamil, Gujarati, Urdu, Kannada, Odia, Malayalam and Punjabi.
• The grid can use 11 digit scripts: Latin, Devanagari, Bengali, Gurmukhi, Gujarati, Odia, Tamil, Telugu, Kannada, Malayalam and Urdu digits. By default the digits follow your language, and you can change them any time.
• In Urdu the interface reads right to left, while the puzzle stays as Sudoku should be.

Any screen, any way up

• Phones and tablets, portrait and landscape. In landscape the grid stays centred with the keypad on one side.
• A “digits on the left” option for left-handed play.
• Light and dark themes in graphite and warm yellow.

• Made for everyone

  • Full TalkBack support: every cell reads its row, column, digit or notes, and says when a digit is marked wrong.
  • Play with a hardware keyboard or D-pad.
  • Large digits, high contrast, reduce motion and vibration settings.

• Gentle reminders, only if you want them

  • Off unless you turn them on. NineSquare offers them once, after you leave a puzzle unfinished, never at first launch.
  • At most one every 3 days, never on a day you’ve played, never after 9 pm, and they stop after two are ignored until you open the app again.

Behind the build

• Native Android: Kotlin and Jetpack Compose, one activity, MVVM with Hilt.
• Offline first, no backend: puzzles ship inside the app as plain text books and are loaded into a local Room database one book at a time, only when needed, so it stays quick on low-end phones. Settings live in Proto DataStore.
• No network calls of its own: the app doesn’t ask for internet access itself. Google Play’s billing library adds it for the optional coffee.
• Graded by technique: the puzzles come from a generator that grades each one by the solving steps it needs. A unit test checks every bundled puzzle against its full solution grid.
• Accessible from the start: screen-reader descriptions, keyboard play and contrast options were designed in with the grid, not added later.
• Moving phones: progress follows you through Android’s own backup.

FAQ