Sudoku
Fill every row, column and 3×3 box with the digits 1 to 9, each exactly once.
Clean finish.
Tap a cell, then tap a number. Keyboard: 1–9 to fill, Backspace to erase. Red digits clash with a row, column or box.
How to play
Every row, every column and each of the nine 3×3 boxes must contain the digits 1 to 9 exactly once. The starting digits are fixed; the rest are yours to fill in. Conflicting digits turn red immediately, so you can correct them before the board fills up.
A calm way to start
Pick the row, column or box with the most digits already placed. One of them usually has only two candidates left, which gives you a foothold without guessing.
Good to know
Every puzzle is generated in your browser with exactly one solution. Easy, medium and hard change how many cells are removed, not the rules. Hint fills one cell you could have worked out yourself.
More ways to unwind
Gravity Shift Blocks ↗Or read how to pick a stress relief game ↗.