Planet Sudoku has multiple puzzle types of Sudoku puzzles including the traditional 9x9 Sudoku, and Samurai Sudoku, plus 25x25 Sudoku, 4x4 Sudoku (great for kids), 6x6 Sudoku, 8x8 Sudoku, 12x12 Sudoku, 20x20 Sudoku, Multi 2 Sudoku, and Multi 4 Sudoku puzzle board designs. Planet Sudoku offers online sudoku puzzles for free, with no downloads, no plugins, and no flash needed, while providing the different difficulty levels, pen designs, puzzle input options, plus integrated online Sudoku solving techniques and much more.

My name is Ivan and I can proudly say I created Planet Sudoku. I started developing Planet Sudoku with many different features in mind and I am really happy with the way it turned out. Planet Sudoku offers the flexibility to handle multiple types of Sudoku puzzles while offering multiple features to the player including saving your progress, a Sudoku training section, multiple input formats, and many features that I hope you and other players will love.

Please, if you have any comments, questions, ideas, or bugs e-mail me at ivan@redbeardsolutions.com

World of Solitaire and World of Card Games

Robert at worldofsolitaire.com is a friend but was also catalyst to help motivate me to accomplish this web site. He is also the creator of a multiplayer card game site worldofcardgames.com.

Noteworthy Sites

Need a break from Sudoku? My friend Marya at worldofcrosswords.com has created a great themed crossword site.

Patrick at www.calcudoku.org has created a nice site with Calcudoku, Killer Sudoku, and Sudoku puzzles.

Thanks

Background Images	We used www.grsites.com for our great backgrounds.
Tango Icon Gallery	Icons used throughout the site.

All javascript, design, and content utilized on his web site are proprietary with all rights reserved, unless specifically documented otherwise.

Common Sudoku misspellings: so do ku, so doku, sodoku, suduku, soduku, sodoko, sudoku, soduko, sundoku, sudoko, suduko

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Sudoku Puzzle Type

PlanetSudoku.com offers the most popular type of Sudoku. PlanetSudoku.com's Sudoku puzzle generation system was built with other types of Sudoku variations in mind including Sudoku X, Alphadoku, Alphadoku X, Killer Sudoku, Killer Sudoku X, and Irregular Sudoku.

Sudoku Puzzle Size

Sudoku puzzle boards can be created in all different sizes. Currently, Planet Sudoku provides the size of 9x9.

One of our objectives to to provide additional Sudoku board sizes such as 3x3, 4x4, 6x6, 8x8, 12x12, 16x16, 20x20, and 25x25.

Sudoku 4x4 Game Design

Sudoku 4x4 puzzles are a great way for learning the base concepts for Sudoku. Valid numbers range from 1 through 4. The logic is the same as the more advanced boards, but just a tad bit easier. This would be a great place to start for kids and beginners.

Sudoku 6x6 Game Design

Sudoku 6x6 puzzles are a little bit more difficult than the Sudoku 4x4 puzzle. Valid numbers range from 1 through 6. Great for kids, beginners, and intermediate Sudoku skill levels.

Sudoku 8x8 Game Design

Looking for something a little bit different than the run of the mills Sudoku 9x9 puzzle? Then the Sudoku 8x8 puzzle might be what you are looking for. Valid numbers range from 1 through 8.

Sudoku 12x12 Game Design

Fun is just starting with the Sudoku 12x12 boards. You will see the introduction of letters to include a unique set of 12 letters and numbers within the Sudoku board. All Sudoku rules still apply.

Sudoku 16x16 Game Design

Sudoku 16x16 puzzles provide a greater challenge to the seasoned Sudoku player. There is a total of 16 valid letters and numbers to make this Sudoku puzzle extra fun.

Sudoku 20x20 Game Design

Sudoku 20x20 puzzles really start relying on letters to solve the puzzle. This is where you really need to concentrate to be able to solve this type of Sudoku puzzle.

Sudoku 25x25 Game Design

Sudoku 25x25 puzzles provide 625 penned and open cells to challenge the most skilled and adventurous Sudoku player. These boards are so hard that my Sudoku board builder has issues pumping out new boards for you to play!

Sudoku Standard Game Design (One Board)

The standard game design for a Sudoku puzzle consists of one board. The actual size of the board will be determined by the Game Size option.

Sudoku Multi 2 Game Design

Sudoku Multi 2 puzzles consist of two boards all joined together on a corner. The boards can be solved individually at a time or at the same time.

Sudoku Multi 4 Game Design

Sudoku Multi 4 puzzles consist of four boards all joined together within the middle. All boards share rows, columns and boxes with two other intersecting boards. The boards can be solved individually at a time or at the same time.

Sudoku Samurai Game Design

Sudoku Samurai puzzles consist of five boards all joined together within the middle. Boards one through four are placed at all four corners, with the fifth board placed in the center. The fifth board shares rows, columns, and boxes with the other intersecting boards. The boards can be solved individually at a time or at the same time.

Sudoku Pen Designs

This feature allows you to choose what type of pen designs you would like to use within selected Sudoku puzzle. We have provided several different options to choose from listed below:

Any Design

Randomly picks Sudoku puzzles of the pen designs listed below.

Randomized

Sudoku penned cells are selected randomly during our Sudoku board generation process. This provides a completely randomized Sudoku penned board.

Criss Cross

Sudoku penned cells are mirrored between four quadrants. For instance, you will see that the top left section of the Sudoku puzzle board will mimic the bottom right.

Vertical

Sudoku penned cells are mirrored from left to right. For instance, the left section of the board will be mirrored to the right.

Horizontal

Sudoku penned cells are mirrored from top to bottom. For instance, the top section of the board will be mirrored to the bottom.

Reflection

Sudoku penned cells are mirrored from the middle of the board to the outside.

Sudoku Puzzle Difficulty

Sudoku puzzle difficulty is determined based on several factors about the individual puzzles. Our system reviews how many open cells there are within the puzzle. Then determines what type and how many logical solving techniques where needed to solve the Sudoku puzzle.

Once that information is gathered, we give the Sudoku puzzle a difficulty score.

Very Easy - Sudoku puzzles that only use the basic solving technique of Naked Single.

Easy - Hidden Single, Naked Pair, and / or Hidden Pair.

Medium - Naked Triple, Naked Quad, Hidden Triple, and / or Hidden Quad.

Hard - Naked Quint, Hidden Quint, Pointing Pair, Pointing Triple, and / or Box Line Reduction.

Very Hard - Jelly-Fish, X-Wing, and / or Sword-Fish.

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