The15-puzzle(alsocalledGemPuzzle,BossPuzzle,GameofFifteen,MysticSquareandmanyothers)isaslidingpuzzlethatconsistsofaframeofnumberedsquaretilesinrandomorderwithonetilemissing.
Thepuzzlealsoexistsinothersizes,particularlythesmaller8-puzzle.
Theobjectofthepuzzleistoplacethetilesinorderfromfirsttolasttilebymovingthetilenexttotheemptyspaceintoit.
puzzlecanbe:
3x3(8-puzzleor9-puzzle),
4x4(15-puzzleor16-puzzle),
5x5(24-puzzleor25-puzzle)or
6x6(35-puzzleor36-puzzle)