Rules
The 9×9 grid is split into nine 3×3 boxes. Fill the empty cells with digits 1 to 9 so that every row, every column and every 3×3 box contains each digit exactly once.
Every puzzle here has exactly one solution, reachable by logic without guessing.
How to use
- Select a cell with a click or tap, then press a digit on the keyboard or on the pad below the board. The small number on a key shows how many of that digit are still missing.
- Keys: 1–9 enter, Backspace/Delete/0 erase, arrows move, N notes mode, Ctrl+Z / Ctrl+Y undo / redo.
- Notes (pencil marks): in this mode digits are written small inside the cell as options, so you do not have to keep them in your head. Pressing the digit again removes the note.
- Candidates fills every empty cell with all allowed digits. With auto-update on, a placed digit is removed from the notes in its row, column and box.
- Hint places one correct digit (in the selected cell if it is empty or wrong). Check highlights wrong digits. The game is saved in the browser, so you can continue after a reload.
Solving tips
- Naked single: if a cell has only one possible digit left, place it.
- Hidden single: if a digit fits in only one cell of a row, column or box, it goes there, even if that cell has other candidates.
- Pairs: if two cells of one unit contain only the same two digits, remove those digits from the other cells of that unit.
- Start with the digits that appear most often, and use notes on the harder levels.