I used to be fond of the #15 puzzle, and even Bobby Fischer was fond of it. The 19nth century puzzle maker Sam Lloyd claimed that he invented it, but it was actually invented by a 19nth century postmaster named Noyes Chapman.
It seems to me that the puzzle is a precursor to the Rubicks' Cube. Both involve sliding pieces in a limited way. It is possible to take apart and reassemble both in a way that can't be solved. https://en.wikipedia.org/wiki/15_puzzle
