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SUDOKU
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Bill

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Sudoku

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Sudoku Rules

Sudoku is a number puzzle where the objective is to fill every row, column and box (3x3 grid) with the numbers from 1-9. Each unit (row, column or box) must have each number exactly once. The game starts with a number of fields pre-filled. Your objective is to fill the rest of the fields without breaking the constraints that each number can only be once in each row, column and box.

6 7 3 9 2 4 5 1 8
8 9 5 1 3 6 4 2 7
1 4 2 7 5 8 6 9 3
2 5 1 4 8 9 3 7 6
9 8 4 6 7 3 2 5 1
3 6 7 2 1 5 8 4 9
5 1 6 8 9 2 7 3 4
4 2 9 3 6 7 1 8 5
7 3 8 5 4 1 9 6 2
6 7 3 9 2 4 5 1 8
8 9 5 1 3 6 4 2 7
1 4 2 7 5 8 6 9 3
2 5 1 4 8 9 3 7 6
9 8 4 6 7 3 2 5 1
3 6 7 2 1 5 8 4 9
5 1 6 8 9 2 7 3 4
4 2 9 3 6 7 1 8 5
7 3 8 5 4 1 9 6 2
6 7 3 9 2 4 5 1 8
8 9 5 1 3 6 4 2 7
1 4 2 7 5 8 6 9 3
2 5 1 4 8 9 3 7 6
9 8 4 6 7 3 2 5 1
3 6 7 2 1 5 8 4 9
5 1 6 8 9 2 7 3 4
4 2 9 3 6 7 1 8 5
7 3 8 5 4 1 9 6 2

Sudoku Strategy

The basic gameplay, which will be enough to solve many easy Sudoku puzzles, is simply to look at an empty field and eliminate all numbers that are already present in the row, column and box it belongs to. In many cases this will be enough to find the correct number. And of course as soon as you've found the right number for one field, it will be easier to figure out other fields in the same row, column or box.

When you get into more difficult situations there are a number of different strategies you can use. The excellent page Sudoku Dragon has a good strategy page that covers many basic strategies as well as some advanced ones.

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About Sudoku

Author image

This online version of Sudoku was made by me, Einar Egilsson. Over there on the left is my current Facebook profile picture. Sudoku is the 14th game I've made, and only the second one that is not a card game or solitaire (the other one being YAHTZEE). I've been planning to create a Sudoku game for a long time, ever since I read Peter Norvig's excellent Sudoku Solver article. The code I wrote to generate and solve Sudoku puzzles for this game is based on his solver. Every puzzle in this game should have a unique solution and be solvable using logic, you should never have to blindly guess. The solver/generator code is available on Github, you are free to use it for whatever you want.

Any comments, questions, ideas for other games or anything else can be sent to admin@cardgames.io.

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This is version 1781 of Sudoku.

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