They're mystery puzzles without instructions. They solve to a word that isn't logically deducible, but once you have it, you feel that it is probably correct. A ton of lateral thinking is needed.
Example: The puzzle shows a maze on six squares. You had to realize that the squares would form a cube, and the maze's squares would thus connect in different ways than on paper.
Example: The entire puzzle consists of a sequence of single-suit mahjong hands that each were one tile away from winning. The solution was, for each hand { determine the waits, sum their numbers, convert the number into letter of the alphabet } and read the letters in sequence.
-- Simon