The 15 Puzzle is a sliding puzzle that consists of 15 numbered tiles in a 4x4 frame, with one empty space. The goal is to arrange the tiles in numerical order by sliding them horizontally or vertically. The puzzle can be solved using various methods, such as solving the first row, then the second row, then the third and fourth rows. However, not all positions of the tiles are solvable, and only half of them can be reached from the starting position. The 15 Puzzle is a classic problem for studying algorithms and heuristics.
It has 7 levels, starting from 4x4, 5x5, 6x6, 7x7, 8x8, 9x9, and 10x10, which add challenge for playing such games. It has 3 different modes: easy, medium, and hard, which make the games more challenging to play.