Sudoku ST

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.