The three rules
- Each row must contain the numbers 1 to 9 without repetition.
- Each column must contain the numbers 1 to 9 without repetition.
- Each 3 × 3 box must contain the numbers 1 to 9 without repetition.
How to use the board
Select an empty cell and press a number on your keyboard or the number pad. Use arrow keys to move, Delete to erase, and N to toggle notes. Starting clues cannot be changed.
Hints are for learning
In practice you can pause, undo and ask for a hint. Hints explain the next step when it can be deduced; direct reveals are labelled as such. Your game is saved in this browser and, with an account, you can sync it across devices. If two versions exist, you choose which to keep. Scored challenges require a verified account, keep the clock running and do not allow hints. Expert level is available for practice.
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