ThinkFun Gordian's Knot Puzzle
Gordian's Knot is one of the world's hardest puzzles to take apart. If you like a serious puzzle challenge, this puzzle is for you-it was designed using a computer and tuned to make the solution incredibly difficult. Comes with a visual instruction booklet that shows how to take it apart and how to reassemble it, for when you get stuck. Designed for 1 player, age 8 and up.