The 'Tricky Games' series are for social entertainment as well as cognitive magic. You might suspect that your eyes just failed yourself? There seem to be no possible way of reaching the solution again. Did the Square just come out of the X, without a hammer, and all the three pieces are safe and sound (refer to IQ901, Square in X)??
Some of the tricky games are ideal promotional items as the aim is easily communicated and the solution intrigouing.