## Sudoku

Today sudoku is, without doubt, the most popular logic puzzle. Although it seems simple, its solving requires numerous strategies. The first sudoku was made about thirty years ago.

## Sudoku variants

Besides classical sudoku, there are many variants that add to the popularity of this puzzle. Here we show you some of them.

### Diagonal sudoku (sudoku X)

Fill in the grid so that every row, every column, every 3x3 box and both long diagonals contain the digits 1 through 9.

## Puzzle |
## Solution |

### Irregular sudoku

Fill in the grid so that every row, every column, and every (irregular) box contains the digits 1 through 9.

## Puzzle |
## Solution |

### Killer sudoku

Fill in the grid so that every row, every column, and every 3x3 box contains the digits 1 through 9. The sum of the cells in a cage must equal the total given for the cage. Each digit in the cage must be unique.

## Puzzle |
## Solution |

### Odd-even sudoku

Fill in the grid so that every row, every column, and every 3x3 box contains the digits 1 through 9. White cells can contain only odd numbers, while coloured cells can contain only even numbers.

## Puzzle |
## Solution |

You can download some of these puzzles in PDF format:

diagonal

irregular

killer