How to play
The rule
Fill the empty squares with 1 to 9 so no digit repeats in any row, column or 3×3 box.
Select, then type
Tap a square, then a number on the pad. “Notes” writes small candidate digits.
When you’re stuck
“Hint” reveals a digit, mistakes can show in red, and “Undo” takes back the last step.
Levels
Each puzzle is made on your device and checked to have exactly one solution before you see it.
| Level | Given digits | What solving needs |
|---|---|---|
| Easy | about 40 | Simple steps only: a square with one possible digit, or a digit with one possible square |
| Medium | about 33 | The same simple steps, with fewer givens |
| Hard | about 28 | May need deeper techniques |
| Expert | as few as possible (usually 22–26) | Can’t be solved with simple steps alone |
FAQ
Does every puzzle have one solution?
Yes. After a puzzle is made, a solver counts its solutions and stops at two; only puzzles with exactly one are shown. We also checked hundreds of puzzles per level with an independent solver.
How do I print a Sudoku?
Press “Print the puzzle”: it prints the puzzle as it started, large and clear on one page, and you can save it as PDF from the print window.
Is my game saved if I close the page?
Yes, in your browser on this device, so you can pick up where you left off.
What are notes for?
They hold the possible digits of a square in small print. When you place a digit, it is cleared from the notes in its row, column and box.