Classic puzzle game. Split photos into pieces and restore the original image!

The task of the game PUZZle is the adjustment of the cutted puzzle pieces to arrange the original image. Piece can be shifted only in the empty adjacent space. It is not possible to move elements diagonally or, just a few fields.
In the game there are 3 levels of difficulty: easy, medium and hard. The game will consist of puzzles in combination (respectively) 3x3, 4x4 and 5x5.