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The game has several difficulty levels. Compared to Easy and Medium Sudoku, the Hard level minimizes the number of digits in the cells. To solve such a puzzle, you need to have the skills to solve the easier levels. This will help you develop some tactics and techniques for solving Sudokus of higher complexity.

Popular methods of solving complex levels

On our site you can play Sudoku for free, without registration. But it is also advisable to print out the game and use different colors or a variety of symbols when solving it. Such tactics will help you keep track of the use of identical numbers in a row, which will avoid unnecessary repetitions. The symbols show the tactics of moves based on previous actions.

The online note-taking function, well thought out and proposed by the developers of, can also be effective. This simple browser notebook helps you to solve complex problems, because it allows you to record all your moves and decisions, to understand the correctness of actions or to recognize mistakes.

There is another effective way of playing that helps to solve complicated Sudokus - the twin tactic. The peculiarity of this method is as follows: in each cell there is an opportunity to mark two numbers at the same time, which match this position. And the player has an opportunity to visually evaluate the whole table and think about further tactics of placing the missing digits. This method significantly reduces the number of possible ways to place the digits in columns and cells.

A similar trial arrangement in cells is also possible with three digits. This variant is called triplet.

We also recommend advanced methods of solving Sudoku, which can be applied to complex levels. The most commonly used methods are called X-Wing, Swordfish, and Y-Wing. They are also applicable to other more advanced puzzle levels - Expert Sudoku and Guru levels.

What are the advantages of solving complex Sudokus online?

There's no question that it's much more convenient to play on your smartphone. There is always free access to the most difficult puzzles. site is equipped with many useful features: there are hints, a notepad for notes. An eraser and a delete function are needed in case of undoing wrong moves. All these tools make it easier to solve a difficult level of the game. Patience and a little effort will make you an expert in complex Sudoku.