About Sudoku
Classic 9×9 sudoku on a moonlit heath: 480 boards in four tiers, from singles to X-Wings and Swordfish, plus a new daily board.
Every board is proven to have exactly one solution that you can reach without guessing. No mistake limit, no countdown.
How to play
- Fill every row, column and 3×3 box with 1–9, each once.
- Tap a cell, then a number. Notes writes pencil marks.
Controls
| Tap a cell, then a number | Place |
|---|---|
| Hold a number | Lock it, then tap cells |
| Arrows · 1–9 · Shift+1–9 | Move · place · note |
| N · Backspace · Z · Y | Notes · clear · undo · redo |
Tips for Sudoku
- Scan by number. Pick a number and check each box: where can it still go?
- Finish nearly-full lines first. A row, column or box with one or two gaps gives the next number cheapest.
- Use notes on harder tiers. Fill notes writes every candidate at once.
Questions about this game
Does every board have one solution?
Yes — each was checked by a solver before it shipped.
Will I have to guess?
No. Every board can be solved by reasoning alone.
What are the tiers?
Apprentice: singles. Adept: pointing and pairs. Warden: triples and quads. Archwarden: X-Wing, Skyscraper, XY-Wing, XYZ-Wing, Swordfish.
Is there a mistake limit?
No.
Progress is saved in this browser.
