Sudoku is a puzzle to place the numbers 1 through 9 into a 9x9 grid of
squares. The large grid of 81 squares is subdivided into 9 small boxes with 3x3 grid of squares. Each of the 9 small boxes should be filled in
with the numbers 1 through 9 only one time each, and each row and each colum of the large grid should be. Any digit from 1 to 9 cannot be repeated
in any of the large grid's rows, colums, or 9 small boxes.
Although the 9x9 grid with 3x3 sub-grids is the most popular, many other variations exist: 4x4 grids with 2x2 small boxes, 6x6 grids with 2x3 small boxes, 12x12 grids with 4x3 squares, 16x16 grids with 4x4 squares, and more.
Sudoku Kingdom runs ranking table which score calculation is based on the level of solved puzzles- Easy, Medium, Hard, Very hard. The score table is cleared at the begging of each month.
Free Online Sudoku Puzzle Solver provides colorful display, timer function, and solve-one-step feature.
Sudoku-Puzzles.net provides countless free sudoku puzzles in five different levels - Very Easy, Easy, Medium, Hard, and Very Hard. And users can select an appropriate level for a game.
Mypuzzle.org offers free sudoku puzzles in seven different levels - Simple, Easy, Mild, Moderate, Hard, Very Hard, and Diabolic. And It allows users to print sudoku puzzles.
Websudoku.com allows players to select a sudoku regarding their level - Easy, Medium, Hard, Evil.
Saidwhat.co.uk provides some variants of sudoku puzzles such as Alphabetic sudoku which uses the letters A - I instead of the number 1-9. Its timer function enables players to set start-time and stop-time.
Fiendishsudoku.com provides five different levels of sudoku puzzles: Easy, Moderate, Hard, Evil, Fiendish. Players can control their grid size of the game display.
Sudoku - mah-jongg.ch supports three levels of sudoku puzzles (easy, medium, hard) and enables players to change the color of a number which they write.
Sudoku - Sudoweb.com provides check function in percentage for what has been done and various levels of sudoku puzzles ranging from Kids to Hard.
Live Sudoku features lots of types of sudoku puzzles in four different levels - Beginners, Medium, Hard, and Wicked. Players can choose a particular puzzle which they want to solve.
Sudoku - Sudogo.com provides free sudoku puzzles with three different skill levels: easy, moderate, difficult.
There are many websites to provide free sudoku puzzles from news media sites:
Sudoku on USATODAY.com offers Sudoku puzzles with options such as timer, showing possible entries for each square, and playing music during game.
Sudoku Games on CBC.ca brings Sudoku puzzles for today and the archived puzzles for the latest 10 days, with options such as timer function and showing possible entries for each square.
Play Sudoku on The Washington Post offers free sudoku puzzles with three different skill levels: Easy, Medium, and Hard.
Sudoku Puzzles - NYTimes.com brings sudoku puzzles with three different skill levels (Easy, Medium, and Difficult) and options such as timer function and Pencil for "not sure numbers".