Sudoku ST
Never a guess, graded by logic
Free · Designed for iPad. Not verified for macOS.
Five difficulty bands, each defined by the solving technique it actually needs — and a generator that rejects any puzzle logic cannot finish.
Sudoku where the difficulty label is a promise rather than a guess.
Every puzzle is graded by the solving technique it actually requires, and every one can be finished by reasoning alone. If the solver cannot complete a puzzle with logic, it is rejected instead of shipped with a label it cannot honour.
FIVE BANDS THAT MEAN SOMETHING
Easy asks for singles only — every step has a cell you can finish outright.
Medium adds locked candidates: a digit trapped in one line of a box.
Hard brings pairs and triples — cells that share their options.
Expert needs a board-spanning move: an X-wing, a swordfish, a chain of colour.
Master needs several of them and long reasoning, but never a guess.
BUILT FOR THINKING
• Pencil marks, with notes that clear themselves when a digit makes them impossible
• Duplicates, matching digits, and the row, column and box you are working in, all highlighted — and each one a setting you can switch off
• A mistake limit you choose, and a hint budget of three, five or unlimited
• Undo, a pausable timer, and hardware keyboard shortcuts
• A number pad in two rows or a 3×3 grid, whichever your thumb prefers
HONEST ABOUT YOUR RECORD
Hinted cells stay marked and never set a best time. Statistics show your best, average and last-ten times with a trend line, current and longest streaks, and how many puzzles you finished unaided.
A REASON TO COME BACK
A daily challenge with a month trophy at eighty per cent of days, and seasonal medal events to work through.
NO ASKS
No advertising. No in-app purchases. No account. No network — the app never connects to anything, so there is nothing to sync and nothing to leak. Puzzles come from a bundled bank of eighty and an on-device generator, which means it works on a plane.
Universal for iPhone and iPad, in portrait and landscape, on iOS 17 or later. VoiceOver labels, values and actions throughout, Dynamic Type, Reduce Motion, and a high-contrast board that follows the system Increase Contrast setting rather than hiding behind its own switch. Every colour on the board is measured against a 4.5:1 contrast floor by a test that reads the shipped assets, not a number in a document.
The interface is in English only for now.
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
This update changes how a puzzle ends and how the next one starts:
• Reach the mistake limit and you can now try the same grid again from the start, or move on to a new one.
• New game starts a fresh puzzle at the difficulty you're already playing, without the difficulty menu. From the pause screen it asks first, so an unfinished puzzle is never thrown away by accident.
The developer, Sagi Stein, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Sagi Stein
- Size
- 4.4 MB
- Category
- Puzzle
- Compatibility
Requires iOS 17.0 or later.
- iPhone
Requires iOS 17.0 or later. - iPad
Requires iPadOS 17.0 or later. - Mac
Requires macOS 14.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
- English
- Age Rating
4+
- 4+
- Copyright
- © 2026 Sagi Stein