Diagonal Sudoku (Sudoku X) Puzzles add another twist to your favorite game: both diagonals must contain all digits from 1 to 9 precisely once.
None of the Puzzles are too easy and they cannot be solved without using the "X" rule..
The books contains 200 Puzzles split into 5 levels of difficulty.
This additional rule forces you to use new solving methods which are explained in the introduction.
Diagonal Sudoku (Sudoku X) Puzzles add another twist to your favorite game: both diagonals must contain all digits from 1 to 9 precisely once