From Max Tillberg:
As engineer in a small country you are assigned to construct the country's road net as soon as possible. The King wants a road to each of his neighbors and he also wants all the roads to be connected. Cities consists of 16 tiles. These tiles are roads, cities (tiles with roads and houses in the middle) and grass. The tile with only grass is called blank. The tiles are supposed to be arranged in such a way that they fulfil three demands: the number of roads leading out of the game plan must be the same as the number of neighbors; the number of neighbors varies depending on the puzzle; all roads must connect to another road or lead out of the game plan; all bricks except the blank must be connected with each other.