How to play Sudoku

Fill every row, column, and 3×3 box so each contains the digits 1 through 9 exactly once.

Select a cell by tapping it, or move with the arrow keys.
Fill with the number pad or keys 1–9.
Erase with ⌫, 0, or the Erase button.
Notes: toggle with N or space to pencil in small candidates.
Hint reveals one correct cell. Duplicates in a row, column, or box turn red.