If you are a Sudoku fan, you will love this FREE EBOOK, we are testing this level of Sudoku and we would like to have your feedback in the reviews or on our page at the link that you will find in the book. To thank you, on the last page you can find the link to get another 500 FREE sudoku puzzles.
This book features 50 extremely difficult Sudoku puzzles that will challenge you, but we can increase or decrease the difficulty level based on your feedback, so we can create the Sudoku you are searching for.