Extreme Sudoku

With so few numbers to start with, almost every square begins with four or five options. You will spend a long time on notes before the first number goes in. The techniques are the same ones used on Expert, plus patterns that link squares far apart on the board.

The puzzle above opens on Extreme. You can switch level at any time with the Difficulty buttons. Every puzzle is checked by a solver to make sure it has exactly one answer.

What extreme sudoku asks of you

• X-Wing. Two rows where a number can only go in the same two columns. The number must take one square in each of those columns, so remove it from the rest of both columns.
• Swordfish. The same idea across three rows and three columns. Rare, but sometimes it is the only way forward.
• Careful bookkeeping. On Extreme a single wrong note can block you for twenty minutes. Check notes after every placed number.

Each of these is explained step by step in our Sudoku strategy guide. Curious how few numbers a puzzle can start with? Read why the answer is 17.

At a glance

Starting numbers	About 22 of 81
Time	Anywhere from 40 minutes to a couple of hours.
Good for	Players who finish Expert and want something that will genuinely push them.
What next	Want a different kind of hard? Try Killer Sudoku on Expert, or a 16 by 16 grid.

Other levels

Questions people ask

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