Sudoku
An installable Sudoku web app with graded puzzles, tutorial-style hints that teach solving techniques, and Apple Pencil Scribble input.
An offline-capable Sudoku app built for iPad and playable in any browser.
- Genuinely graded puzzles — generated client-side and graded by the human techniques required to solve them, so Easy through Very Hard reflect real solving difficulty. A Custom mode lets you key in a puzzle from a newspaper or book and play it with full assistance.
- Hints that teach — each hint names the technique it applies (naked and hidden singles, pointing pairs, box-line reduction, naked and hidden pairs, naked triples, X-Wing, Swordfish, XY-Wing, and unique rectangles), highlighting the pattern cells that justify the move and the candidates being eliminated, with multi-step hints you can step through one inference at a time.
- Play aids — pencil-mark notes with automatic cleanup when related cells are filled, one-tap candidate fill for a cell or the whole board, per-digit remaining counts, undo and redo, and optional highlighting of peers, matching numbers, legal placements, and conflicts.
- Flexible input — enter digits by touch, keyboard, or by writing with an Apple Pencil via Scribble.
- Picks up where you left off — games save automatically and resume, and error, hint, and reveal counts carry through to the completion screen. A service worker keeps the whole app playable offline.