Created as "Number Place" in the 1970s, this logic puzzle gained mass popularity in Japan in the 1980s. "Sudoku", or "Su Doku", is Japanese for "number singly." In 2005 it gained great appeal in the United Kingdom and is rapidly expanding to the rest of the Western Hemisphere. The aim of the puzzle is to place a number from 1-9 in every square in the grid so that every row, column and 3x3 "region" includes each number once only. While numbers are most often used, this is only for simplicity. No math is required, only logic. There are also variants using letters or symbols, different-sized grids, overlapping grids, and other variations.
Single daily Sudoku puzzle, 5 different levels (easy to very difficult), playable online (Flash required) and printable to PDF.
Offers classic Sudoku and variants, as well as an online solver.
Article by Paula Dear. Covers history in Japan and the UK and compares to the Rubik's cube craze of the 80s.
Daily Sudoku, Jigsaw, and Killer puzzles. Interactive Sudoku solver/teacher and tutorials.
Offers daily printable puzzles of varying difficulties, including Sudoku for Kids. Also offers archive of past puzzles, tool for rendering custom puzzles, FAQ, and books for purchase.
Offers a different printable puzzle each day. Also includes solutions and FAQ.
Easy printing of 6 sudokus per page.
Clean site with many puzzles at all levels, solvable online.
Free online sudoku. Offers online game on 5 difficulty levels, changeable skins and printing up to 4 sudoku boards on one sheet of paper.
Solve Sudokus online. With explanation of some common solving strategies.
Offers a tutorial for creating puzzles, a Java-based solver, and links to other resources. [English/Japanese]
solve Sudoku puzzles online, 5 levels, clean interface
Site with a very large number of puzzles and variants (4x4...25x25, Multi 2, Multi 4, Samurai Sudoku, etc.). Beginner to expert, solving engine, training aids, and "app-like" user interface.
Flash version of the Sudoku game. Also offers solution.
Offers five difficulty levels.For each sudoku ,You can print with normal and candidate mode.
Many printable sudokus downloadable as PDF. New ones generated often.
Offers competitions for prizes. Traditional Sudoku, Godoku (letters) and Super Sudoku (16x16).
Offers a daily puzzle, books, software, and related merchandise. Also offers puzzles for syndication.
solve Sudoku puzzles online, 3 levels, interface a bit clunky
A scratch pad to help you fill in a Sudoku puzzle. You still have to solve it yourself. Every day, you get three fresh Sudokus.
Solves puzzles based on inputted information.
Step by step guide to solving sudoku puzzles. Goes from basic to advanced techniques.
Provides sudoku puzzles in easy, medium and hard levels with their solutions. Also provides facility for daily email sudoku newsletter.
Play sudoku puzzles online for free.
Collection of printable grids, ordered by difficulty level. Solutions provided. Includes rules and solving methods.
Two daily sudoku puzzles (easy and medium), printable and solvable online.
Sudoku information and downloadable puzzles (PDF) in four levels and five languages (English, Spanish, German, French, Italian).
Solve Sudoku online, download printable puzzles at all levels, descrptions of strategies. Windows programs for solving and printing Sudoku, and for solving Samurai Sudoku.
Sudoku solver. Offers free puzzles at 3 levels of difficulty (easy, normal, hard) and a practical stopwatch.
Several programs in different languages for analyzing possible Sudoku combinations.
Sudoku generator, editor, solver. User registration and rankings.
Online sudoku solving with a very clean interface.
Blog with 5 sudoku puzzles each day, from "very easy" to "extreme".
Free online generator, solver, and helper. [English/French/Spanish/Polish]
Offers daily puzzle in PDF format. Includes archive, FAQ, and a "dozen" variant.
Solve Sudoku online with a very clean interface.
Free, daily Sudoku puzzles to print or play online.
Free daily puzzles with five difficulty levels with their solutions. Also offers guide to solve Sudoku puzzles.
Solve Sudoku puzzles online, with interface targeted to tablets.
4 levels of online playable Sudoku. Print up to 6 sudokus on one A4 sheet. Requires Flash.
Offers four difficulty levels. The puzzles can be solved online or downloaded as a PDF file. [English/German/French/Spanish/Dutch/Portuguese/Italian]
A SuDoku helper (not a solver) that replaces pencil and paper to aid solving.
Free daily printable Sudokus. Also offers history, rules, and solving techniques.
Free daily puzzles with five difficulty levels. Also offers printable e-book.
Today's daily Sudoku puzzle from www.dailysudoku.co.uk.
Article by David Smith covering the puzzle's origins as "Number Place" by Dell Puzzle Magazine in New York in the 1970s.
solve Sudoku online, 5 levels
Offers a database of crafted puzzles, organized by difficulty. Also offers FAQ and forum. [Norwegian/English]
An encyclopedia entry describing the rules, history, strategies and variants of Sudoku. Notes that these are a type of "Latin square" which have been analyzed since ancient times.
Information on the 2006 World Sudoku Championship held in Italy. Includes background information, events, results and FAQ. [English, Italian]
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