What makes it different
- Hints that teach. Every hint has three steps: first the technique and the row or box to look at, then the cells and candidates, and finally applying it. For example: “In row 3, 7 fits in only one cell”. In Uzbek, Russian and English.
- Mistakes come first. With a wrong digit on the board logical steps mean nothing, so the hint finds it first.
- No guessing. Each of the 4,000 base puzzles has one solution, and a program has checked that human techniques solve it to the end. The level comes from that solving path, not from how many digits are given.
- No repeats. Each game relabels digits and shuffles rows and columns: the difficulty stays, the board is new.
- It saves. Close the page and the game is still there, saved per level, along with your time.
Five levels
| Level | Given digits | Techniques needed | Best for |
|---|---|---|---|
| Easy | 34–40 | singles only | beginners, a quick game |
| Medium | 27–35 | locked candidates or a pair, 1 to 3 times | those comfortable with the rules |
| Hard | 24–34 | triples and quads, or at least four pairs and locks | those who use notes |
| Expert | 24–34 | X-Wing, Swordfish, XY-Wing, XYZ-Wing | experienced players |
| Master | 23–34 | coloring, X- and XY-chains | those after a real challenge |
The level comes from the hardest technique needed and the number of hard steps, not from the given digits. So even a 34-clue puzzle can be Master level. The techniques, with examples.
How to play
- Pick a level. No name, password or e-mail.
- Tap a cell then a digit, or a digit then cells: both flows work with no setting to change.
- Notes mode writes small candidates; “Fill” adds every possible digit to every cell in one tap. Placing a digit updates the notes of its peers automatically.
- Each digit is used 9 times: the small number on its key shows how many are left, and finished digits dim.
On phone and desktop
On a phone the keys sit under your thumb and the board stays crisp on any screen. On a landscape phone or a computer the board is on the left and the keys on the right. On a computer the keyboard is faster:
| Key | Action |
|---|---|
| ← ↑ ↓ → | move the selection |
| 1–9 | place a digit (in notes mode, a note) |
| Shift + 1–9 | one note without switching mode |
| N | notes mode |
| Z / Y | undo / redo |
| H | hint |
| Backspace | erase |
| P | pause |
FAQ
Is it free?
Yes: every level, the daily puzzles and duels are free. The site runs on ads.
Do I need an account?
No. Your results stay in your browser. For the leaderboard you choose a name yourself.
How do hints affect my result?
In solo play the hint count appears in your result, and best times count only games without hints. On the daily leaderboard results with hints go to a separate table.
What if my connection drops?
A game in progress keeps going: the solver runs in your browser. Only the leaderboard and duels need a connection.
Sudoku rulesfor beginners
Daily sudokuthree a day, with a leaderboard
Sudoku techniquessingles to X-Wing, with examples
Sudoku duelrace a friend