Sudoku
Fill every row, column and 3×3 box with 1–9.
Time0:00
Mistakes0
Best—
How to play: tap a cell, then tap a number. Turn Notes on to pencil in candidates instead. Given numbers can’t be changed. Wrong entries show in red — fix them to win. Arrow keys, digits, Backspace, N for notes, H for hint and U for undo also work on a keyboard. On a phone you can add it to your home screen from your browser’s share menu. Once loaded, it works offline too.