Welcome to FullSudoku.com — the Sudoku portal
FullSudoku.com is the portal dedicated to online Sudoku. Here you’ll find every Sudoku variant under one roof: the classic 9×9, the challenging Mega Sudoku 16×16, the arithmetic Killer Sudoku, the spectacular Samurai Sudoku with five overlapping grids, and the Daily Sudoku challenge.
No mandatory sign-up, no downloads, no intrusive ads. Four difficulty levels (easy, medium, hard, expert) so you can improve at your own pace.
History of Sudoku
Sudoku has its roots in the Latin squares of the Swiss mathematician Leonhard Euler (1783), but the modern puzzle was created by Howard Garns, a retired American architect, in 1979 and published under the name Number Place.
In 1984 the Japanese company Nikoli adopted the game, gave it the name 数独 (Sudoku, "single number") and added the rule of minimal, symmetric clues. The craze reached Europe in 2004 thanks to the New Zealand judge Wayne Gould, who convinced The Times of London to publish them.
Basic Sudoku rules
The grid is 9×9 cells divided into nine 3×3 blocks. The goal is to fill every empty cell with a number from 1 to 9 following three rules:
- Each row contains the digits 1 to 9 without repeating.
- Each column contains the digits 1 to 9 without repeating.
- Each 3×3 block contains the digits 1 to 9 without repeating.
A well-formed Sudoku always has a unique solution. No advanced maths is needed, only logic and observation.
Techniques for solving Sudokus
Naked single: if only one number fits in a cell, place it. Hidden single: if a number can only go in one cell within a row, column or block, place it there. Naked pairs: two cells that share exactly the same two candidates remove those candidates from the rest of the group. X-Wing and Swordfish: advanced techniques for expert-level puzzles.
Cognitive benefits of Sudoku
Solving Sudokus daily improves working memory, stimulates logical-deductive reasoning, reduces stress and is associated with preventing cognitive decline. A study published in the International Journal of Geriatric Psychiatry found that older people who practise puzzles have a mind up to ten years younger.