Basic Rules of Sudoku

* There is only one valid solution to each Sudoku puzzle. The only way the puzzle can be considered solved correctly is when all 81 boxes contain numbers and the other Sudoku rules have been followed.

* When you start a game of Sudoku, some blocks will be pre-filled for you. You cannot change these numbers in the course of the game.

* Each column must contain all of the numbers 1 through 9 and no two numbers in the same column of a Sudoku puzzle can be the same.

* Each row must contain all of the numbers 1 through 9 and no two numbers in the same row of a Sudoku puzzle can be the same.

*Each block must contain all of the numbers 1 through 9 and no two numbers in the same block of a Sudoku puzzle can be the same.

Sudoku Solution When the rules are applied, the solved Sudoku puzzle appears as shown:

How to Play Sudoku

The sudoku grid consists of eighty-one squares in a nine by nine grid. To solve the sudoku, each square in the grid must contain a number between one and nine, with the following conditions:

* Each row of nine cells must contain each of the numbers from 1 to 9 once and only once.
* Each column of nine cells must contain each of the numbers from 1 to 9 once and only once.
* Each of the nine 3 by 3 boxes of nine cells must contain each of the numbers from 1 to 9 once and only once.

Every Sudoku games begins with a number of squares already filled in, and the difficulty of each game is largely a function of how many squares are filled in. The more squares that are known, the easier it is to figure out which numbers go in the open squares. As you fill in squares correctly, options for the remaining squares are narrowed and it becomes easier to fill them in. The Sudoku games on playsudokugame.blogspot.com let you check your progress as you go, to help prevent going down a wrong path.

Anil Kapoor

History of Sudoku Game

The puzzle was designed by Howard Garns, a retired architect and freelance puzzle constructor, and first published in 1979. Although likely inspired by the Latin square invention of Leonhard Euler, Garns added a third dimension (the regional restriction) to the mathematical construct and (unlike Euler) presented the creation as a puzzle, providing a partially-completed grid and requiring the solver to fill in the rest. The puzzle was first published in New York by the specialist puzzle publisher Dell Magazines in its magazine Dell Pencil Puzzles and Word Games, under the title Number Place (which we can only assume Garns named it).

The puzzle was introduced in Japan by Nikoli in the paper Monthly Nikolist in April 1984 as "Suuji wa dokushin ni kagiru" , which can be translated as "the numbers must be single" or "the numbers must occur only once" . The puzzle was named by Kaji Maki, the president of Nikoli. At a later date, the name was abbreviated to Sudoku (pronounced SUE-dough-coo; su = number, doku = single); it is a common practice in Japanese to take only the first kanji of compound words to form a shorter version. In 1986, Nikoli introduced two innovations which guaranteed the popularity of the puzzle: the number of givens was restricted to no more than 32 and puzzles became "symmetrical" (meaning the givens were distributed in rotationally symmetric cells). It is now published in mainstream Japanese periodicals, such as the Asahi Shimbun. Within Japan, Nikoli still holds the trademark for the name Sudoku; other publications in Japan use alternative names.

In 1989, Loadstar/Softdisk Publishing published DigitHunt on the Commodore 64, which was apparently the first home computer version of Sudoku. At least one publisher still uses that title. Yoshimitsu Kanai published his computerized puzzle generator under the name Single Number for the Apple Macintosh [11] in 1995 in Japanese and English, and in 1996 for the Palm (PDA).

Bringing the process full-circle, Dell Magazines, which publishes the original Number Place puzzle, now also publishes two Sudoku magazines: Original Sudoku and Extreme Sudoku. Additionally, Kappa reprints Nikoli Sudoku in GAMES Magazine under the name Squared Away; the New York Post, USA Today, The Boston Globe, Washington Post, and San Francisco Chronicle now also publish the puzzle. It is also often included in puzzle anthologies, such as The Giant 1001 Puzzle Book (under the title Nine Numbers).

Within the context of puzzle history, parallels are often cited to Rubik's Cube, another logic puzzle popular in the 1980s. Sudoku has been called the "Rubik's cube of the 21st century".

Anil Kapoor

Sudoku Meaning

In Sudoku "Su" means number in Japanese language, and "Doku" refers to the single place on the puzzle board that each number can fit into. It also connotes someone who is single—indeed, one way to describe the game is "Solitaire with numbers." Sometimes it is mis-spelled as "soduko" or "sudoko." Although its name is Japanese, its origins are actually European and American, and the game represents the best in cross-cultural fertilization. Unlike many games which spring from one culture and are then absorbed by others, Sudoku's development reveals it to be a true hybrid creation.

Sudoku's future development is unknown. While the 9 by 9 grid is the most common form of Sudoku, there are many variants of the game. Four by four (4 x 4) Sudoku with 2 by 2 subsections are simpler, fun for younger audiences, and easy to deliver to mobile devices like cellphones (this site offers a 4 by 4 variant). There are 5 by 5 games, 6 by 6 and 7 by 7 games. For the truly addicted, there are even 16 by 16 grids, not to mention a 25 by 25 grid apparently offered by Japanese game developer Nikoli. Sudoku puzzles using letters and symbols, some even spelling words in their final solutions are also becoming available. Other variants require computational skills.

The closest puzzle to compare to Sudoku is perhaps the humble jigsaw. There are similarities both in the way it works and the pleasure gained by solving it. In a jigsaw there are lots of pieces to fit in a particular grid, there is only one solution and (normally!) each piece can only go in one place. Sudoku is somewhat similar in that is a matter of putting things in the right place. If you like doing jigsaws you'll probably enjoy Sudoku too.

Anil Kapoor

Sudoku Introduction

The word Sudoku means "single number" in Japanese language. This name is a registered trademark of a Japanese company - Nikoli Co. Ltd in Japan, as Tetris is in North America and Europe. The game is not a math quiz - it's a logic puzzle where your brain is trained in the ability to see similar and avoid it anywhere.

Sudoku is easy to learn but a challenge to player. If you're new to Sudoku, see How to Play link in side panel for a brief introduction to this brain-bending game of numbers and logic. Spend a few minutes familiarizing yourself with the rules of Sudoku and you'll be ready for hours of fun.

Sudoku Game is played over 9x9 grid, in each row there are 9 slots, some of them are empty and need to be filled
Each row, column and “area” (3*3) should contain the numbers 1 to 9 however:
* Number can appear only once on each row
* Number can appear only once on each column
* Number can appear only once on each area (3*3 slots)
* Number should appear only once on row, column or area.

Anil Kapoor