Are you finding Sudokus not challenging enough? Are you disappointed by supposedly difficult puzzles? Can you solve every riddle? That ends now - I promise! These over 200 Sudokus become more intense from puzzle to puzzle. It starts at incredibly difficult and ends at unsolvable. Yet, each of these puzzles always has only one possible solution - that’s a promise too. You will surely be frustrated.

In your hands, you hold the 13th volume of my puzzle library, and I thank you for your purchase. The difficulty of the individual puzzles continuously increases in this book! It starts very hard and gets progressively harder to solve the Sudokus. Are you often finding Sudokus not challenging enough? This book puts an end to that! Here you will find the most difficult known Sudokus, and I am sure you will need days to solve even just one.