non-canon The Dune Encyclopedia. The basic strategy in the game is to harvest spice from the treacherous sand dunes using a harvester vehicle, convert the spice into credits via a refinery, and to build military units with these acquired credits in order to fend off and destroy the enemy. The game map initially starts with a fog of war covering all area which is not covered by the player's units range of view. As the units explore the map, the darkness is removed. Unlike later games such as Warcraft II: Tides of Darkness, the fog of war is lifted forever with initial exploration; it does not become dark once more when units leave the area. In addition to enemy incursions, there are other dangers such as the marauding, gigantic sandworm, capable of swallowing vehicles and infantry whole but blocked by rocky terrain. The player can only build on rocky terrain and must build concrete foundations to avoid deterioration of the structures due to the harsh weather conditions. Structures will still gradually decay over time regardless of the presence of those concrete slabs, but they save repair costs in the long run. Spice fields are indicated by orange coloration on the sand, darker orange indicating high concentration. Some spice may be concealed as bumps on the terrain (a "spice bloom") that become spice fields when they are shot at, or when a unit runs over them (the unit is destroyed in the ensuing "spice blow"). A map of the planet Arrakis is shown before most missions, where they can choose the next territory to play in among two or three. This affects primarily the enemy house fought in the next mission, as all missions except the first two require the destruction of the enemy. Nine territories must be fought, irrespective of house, to reach the endgame. Some key elements that first appeared in Dune II and later appear in many other RTS games include: A world map from which the next mission is chosen Resource-gathering to fund unit construction Simple base and unit construction Building construction dependencies (technology tree) Mobile units that can be deployed as buildings Different sides/factions (the Houses), each with unique unit-types and super weapons A context-sensitive mouse cursor to issue commands (introduced in the Mega Drive/Genesis version) Completing higher missions gives authorization to use improved technology and higher-order weaponry unique to each House, ensuring varied game play.