- 250 best puzzles + surprise in 250 classic killer sudoku very hard (need to download and print)Labyrinth - the most popular game in the world - a boring, dynamic gymnastics for the mind. Your logical thinking tends to bright, creative non-standard solutions. This book is your friend in achieving mastery of Sudoku.- 250 Very hard levels- all riddles have only one verified solution- 2 puzzles on 1 page, very practical and convenient- a lot of free space for the progress of your thoughts- good mind support in excellent form- large font- develops memory, logical thinking, helps to focus- creative possibilities are expandingIdeal gift for all fans of puzzles. An excellent book for free time and learning of the mind. I hope you enjoy the book. I would be very grateful if you write a review.Best regards,Andrii Pitenko