Nothing is more beautiful than achieving a great victory. Against the puzzle and against the author - or are you perhaps even fighting against yourself? Maximum difficulty Sudokus await in this book, and who doesn't know that feeling of having succeeded? Letting the pencil drop, leaning back, relaxing your shoulders... smiling - and on to the next battle! The currently most sought-after Sudoku developer in the world, Stefan Heine, guarantees with his name 500 hard to extremely hard, error-free, and unique Sudokus in this book.