The success or lack of it for any attempt at solution may not become apparent until most of the pieces are in place. For a geometrical puzzle, ideally all pieces are dissimilar and non-symmetrical, thus resulting in the maximum number of combinations for a given number of pieces.
Maximum difficulty is achieved when only one correct combination exists.
Since puzzles of this type can usually be made more difficult simply by increasing the number of pieces, the challenge facing the puzzle designer is to cleverly devise simple puzzles of this sort having few pieces while yet being intriguing and puzzling. In this chapter, we will introduce the subject by considering some simple two-dimensional combinatorial puzzles.