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Sudoku encyclopedia

Everything about Sudoku in one place, written plainly and checked against its sources. Every section lists where its facts come from.

History

The history of Sudoku

From a 1979 American puzzle magazine to newspapers all over the world.

Where the name Sudoku comes from

A Japanese phrase, a trademark, and why Japan also says Nanpure.

Rules and variants

Sudoku rules, explained

The three rules, the words players use, and what makes a puzzle fair.

Sudoku variants: Killer, Jigsaw, Diagonal, Samurai and more

Sums, odd-shaped regions, diagonals, giant grids and mini ones.

Killer Sudoku

Cages, sums and the handy 45 rule.

Math and computing

The mathematics of Sudoku

How many grids exist, why 17 clues is the minimum, and Sudoku as graph colouring.

How computers solve Sudoku

Backtracking, exact cover and solvers that think like people.

How Sudoku difficulty is rated

Why clue counts mislead, and rating by technique.

People and competitions

The World Sudoku Championship

Timed rounds, classic and variant puzzles, since 2006.

People who shaped Sudoku

The puzzle maker, the father of Sudoku, the judge and the setters.

Sudoku and you

Is Sudoku good for your brain?

What a large 2019 study found, and what it cannot tell us.

Sudoku in newspapers and on television

The newspaper boom, the first TV shows, and Sudoku every day.

Want more boards like this?

We also make a Sudoku app for iPhone, iPad, Mac and Android. There are no ads in it at all, it works offline, and when you ask for a hint it shows you the technique instead of just filling in a number.

App StoreiPhone, iPad, Mac Google PlayAndroid

Sudoku Flow is made by Rubigo Games, the developer of the Sudoku app recommended on this site.