# Odd / Even Sudoku

Welcome to odd / even sudoku. If you've not come across this puzzle before, it is like standard sudoku but with a little twist!

Whereas many sudoku variants add extra regions - for instance the distinctive diagonal 'X' created by adding the constraint that the diagonals also contain 1 - 9 only, the odd / even sudoku puzzle adds an informational constraint.

This constraint is that, at the start of the puzzle, you will notice that various cells in the puzzle are coloured. Now, all the cells in a coloured region are either all odd, or all even. However, you need to work out which it is as you go through the puzzle. Once you know, you will need to use this fact to help you to solve the puzzle. Play a Sample Odd Even Puzzle and then try the hundred puzzles below!

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