A truly good puzzle is a rare thing. It has to be challenging but fair, with a solution that is isn't immediately evident but instead deducible only by those who buckle down and set their minds to it.
Cleopatra: Riddle of the Tomb, a traditional point-and-click adventure, has many conundrums of this sort; puzzles that have the potential to break the brains of both rookie players and seasoned solvers, but become obvious to all once they are finally understood. Unfortunately, it also has a number of seemingly unreasonable riddles the answers to which remain opaque even after the puzzle has been successfully solved.
