What is Sudoku X?
Sudoku X is very similar to normal sudoku but there is one extra constraint or rule. That rule is that the two longest diagonals (from top left to bottom right and top right to bottom left) must also contain each number in the puzzle once only. This makes the puzzle easier, but then it gives the puzzle setter the opportunity to give you even less numbers to start, leaving you to use the new rule to deduce the answer – make no mistake sudoku X can be very hard, but is great fun!
