Sudoku game rules

Volodymyr Sakhan · January 25, 2009 · Updated April 16, 2026

While solving the puzzle, you need to follow one sudoku rule only. You have to fill in the blank cells with numbers from 1 to 9, so that:

In any line

Correct line filling:

Incorrect line filling:

In any column

Correct column filling:

Incorrect column filling:

In any square

Correct square filling:

Incorrect square filling:

numbers were used only once without any repetitions.

Game features

By pressing “Reset” while solving sudoku, you will cancel all the moves made after confirmation.

To cancel a move, press a cross near the number you inserted.

There a two game modes: simple and advanced.

In the simple mode you can put only one number in a blank cell.
In the advanced mode you make a single click to insert one or several suitable numbers in a cell, or a double click to insert a number (rejecting other options) like in the simple mode.

After a successful completion of sudoku, you will see how your level and points have changed, and also your rank among other competing players.
Traditionally, a random phrase of great or just famous person is shown.

Terms and conditions

While on this website, you must follow certain rules.
It is prohibited to:

dishonestly enhance your solution results with the help of any foreign programs, scripts or code injections;
insult other players and use adult language in the game, in the chat or on the forum;
or violate the competitive spirit of “Sudoku online” in any other way.

For these violations, the administration reserves the right to immediately and without any explanation carry out the punishment for the player, including blocking their player account.