On the Subject of Fifteen
Somebody ate the sixteenth.
The Fifteen module displays on its front surface a grid in a 4×4 arrangement with 15 tiles numbered 1 to 15, and an empty space. The module can be disarmed by sliding tiles from their current position into the empty space until the complete arrangement matches a goal arrangement to be determined as outlined on the following page (Page 2).
In addition to the tiles labeled 1–15, the empty space (which does not contain a numbered tile) contains a number shown in green coloration. This number shows the maximum number of moves that are permitted to be made to disarm the Fifteen module. As a tile is moved into the empty space, this number decrements (is reduced by 1). Running out of moves before the tiles are in the correct positions according to the goal arrangement obtained from the instructions on the next page (Page 2) will result in a strike; furthermore, the tiles on the module will revert to their original arrangement and the module expects all of the correct moves to be made again.
A tile can be made to slide into the empty space by tapping the tile you wish to move. Only tiles that are orthogonally adjacent to the empty space (directly neighboring either above, below, to the left or right, but not diagonally) can be moved. Tapping any other tile will result in a strike; however, unlike the situation outlined in the previous paragraph, their arrangement does not revert.
To find out what the desired goal arrangement is, use the instructions on the following page (Page 2).