The " 15 "

The game of 15 is a game that falls within the of the solitary category, a perfect pastime while waiting.
It consists of a base which acts as a support to 15 tiles numbered from 1 to 15 obviously.
The game is very simple:
You've to move the tiles in the 4 directions using the free space to perform the movements to arrange them properly in ascending order.
My version consists of 130 pieces, the size of the base are very small: 12x12 studs, while the tiles are big 2x2 studs.
In the pictures you can see black lines, they are only to mark the tiles, 'cause in rendering the edges are not seen.