The 15-puzzle (also called Gem Puzzle, Boss Puzzle, Game of Fifteen, Mystic Square and many others) is a sliding puzzle that consists of a frame of numbered square tiles in random order with one tile missing.
The puzzle also exists in other sizes, particularly the smaller 8-puzzle.

The object of the puzzle is to place the tiles in order from first to last tile by moving the tile next to the empty space into it.

This game consists two puzzles in one game scene.
When you move tile in any of two puzzles mirroring piece in other puzzle moves too,
so by solving any of two puzzles you solve both of them at a same time.

puzzles can be:

clasic (numbered tiles),
emoji images,
all kind of pictures;

3x3 (8-puzzle or 9-puzzle),
4x4 (15-puzzle or 16-puzzle),
5x5 (24-puzzle or 25-puzzle) or
6x6 (35-puzzle or 36-puzzle)