But it is a known fact that in 1878 Sam Loyd, America’s puzzle-expert, “drove the whole world crazy” with his newly “discovered” 14-15 puzzle (though some accounts state that, other authorities dispute this fact). Sam Loyd claimed from 1891 until his death in 1911 that he invented the puzzle. Actually, he had nothing to do with the invention or popularity of the game… This was a variation on the “15 Puzzle” which was made and sold by the Embossing Company from New York about 10 years earlier!

The “15 Puzzle” consists of 15 squares numbered from 1 to 15 which are placed in a 4×4 box leaving one position out of the 16 empty. The goal is to reposition the squares from a given arbitrary starting arrangement by sliding them one at a time into the configuration shown above (for some initial arrangements, this rearrangement is possible, but for others, it is not).

It was not surprising that Sam Loyd drove the whole world crazy by his variation of the puzzle of 15. The problem that he formulated was impossible to solve. When you bought Loyd’s 14-15 puzzle the empty square was positioned bottom right. The pieces were numbered in order from left to right and from top to bottom; only the pieces numbered 14 and 15 were reversed. You should re-order the pieces so all the pieces are in the correct position and the empty place should be positioned bottom right again. A slide puzzle with square pieces can only be solved when the number of exchanges necessary to solve the puzzle is even.