Match your mind with the world's greatest brains! If you can match minds with the greatest brains, then you have a chance of solving these puzzles. Try this one
FLEX YOUR brain power like never before! From acclaimed author Dr. Gary Gruber, whose proven critical-thinking methods have sold more than seven million books,
If you're an experienced sudoku puzzle solver looking for a real challenge, then the World's Hardest Sudoku Book: 200 of the World's Toughest Sudoku Puzzles (Vo
This book contains AI Escargot, the world famous sudoku puzzle which became the most difficult sudoku puzzle known in 2006. There are also several hints for sol