Warning! Only the most skilled sudoku experts should try these mind-blowing puzzles!
In this series, you will find puzzles truly worthy of the label "hard." The four volumes of this series range from Level 1 to Level 4, increasing in difficulty with each book. At Level 4, even the fearless approach the mind-melters inside with trepidation.
In this series, you will find puzzles truly worthy of the label "hard." The four volumes of this series range from Level 1 to Level 4, increasing in difficulty with each book. At Level 4, even the fearless approach the mind-melters inside with trepidation.