Sudoku

How to play

1. Select an editable cell, then choose a digit from the number buttons or type it. Arrow keys move the selection; Erase, Backspace, or Delete clears it.
2. Turn Notes on (or press N while on the board) to save possible digits in a cell. Choose a note again to remove it. Entering a number clears that cell's notes and removes that digit from related row, column, and box notes.
3. Given digits stay fixed. Repeating a digit in a row, column, or box is rejected without changing your saved board.
4. An accepted entry is not a hint that the digit is correct. The puzzle completes when the entire grid is correct.

Head-to-head rules

Complete the Sudoku grid correctly before your opponent. Both players get the same puzzle and start together, with 10 minutes to finish. Completion time decides the match; fewer moves or a higher solo score do not beat an earlier correct finish. Finishes within 0.1 seconds draw. If neither player finishes before time runs out, the match is a draw.

Your moves and answers stay private. Leaving through the game controls forfeits the match; closing the page does not pause its clock.

Real-player matches update this game's own Elo rating. Daily and practice results keep their separate progress and never change Elo.