Sudoku puzzles are a tantalizing challenge - and an excellent way to develop and utilize your logical thinking skills. This publication presents 501 really hard 9 x 9 Sudoku puzzles. The first 450 are traditional puzzles with the numbers 1 through 9. The final 51 puzzles are an extreme challenge because they contain letters, symbols, and various combinations of the two, which will test your ability to use your Sudoku wisdom with non-traditional characters. Sit down, with a pencil and eraser in hand, and immerse yourself in this wildly entertaining - and addictive - logic game!.