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The sudoku guides

Direct, sourced and dated answers, from the team that makes SudoKoum. No content-farm filler.

Sudoku techniques: the 5 levels, from last free cell to Swordfish

Each difficulty tier maps to specific techniques. Here they are, in the order you will need them.

How to play sudoku with friends: the asynchronous challenge guide

Real time or turn-free, how a link-based duel works, and five ideas to get your family or office hooked.

Is sudoku good for your brain? What the science actually says

A study of 19,000 adults, prefrontal cortex imaging, and the caveats the miracle sellers leave out.

Sudoku without ads: why it is so rare and how to find one

The three business models of mobile sudoku, and how to spot an app that respects your time.

And to pick your app: the 2026 comparison SudoKoum vs Sudoku.com and Brainium. Social modes, real prices, ads, verified and dated.

Solving techniques

The X-Wing sudoku technique needs four cells and one digitHow the X-Wing works in sudoku, shown on a checked grid where the 9 in rows 4 and 8 removes five candidates, plus the mistakes that fake an X-Wing pattern Y-Wing in sudoku uses three cells to cross out one digitY-Wing, also called XY-Wing, links a pivot to two pincer cells and removes one digit. See how to spot it, step by step, on a sudoku grid checked by a script Hidden pairs in sudoku show up when you track each digitHidden pairs in sudoku explained on a script-checked grid, with the 7 and 9 of row 7, the nine candidates you can remove and the mistakes that fake a pair

How to solve and improve

How to solve sudoku step by step as a complete beginnerSolve your first sudoku using logic alone, from the rules to hidden and naked singles, with two checked grids and the loop to run when no cell will fill

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