Symply'X app for iPhone and iPad

SymplyX for iPhone not so simple.
The "15 Puzzle" consists of 15 squares numbered from 1 to 15 which are placed in a 4x4 box leaving one position out of the 16 empty.
The titles of the configurations are: horizontal, vertical, taquin et 30. The images on the buttons show the end configuration. The 30 configuration is a magic square with 16 pieces numbered form 0 (empty space) to 15 with the instruction to slide the pieces so that the sum of all rows and the sum of all columns and the sum of the diagonals equals 30 The little buttons, on the top, are for enable / disable the sound and for shuffle of the pieces. Also, the shuffle is possible with a shake gesture.