In Warcraft II, as in many real-time strategy (RTS) games, players collect resources to produce buildings and units in order to defeat an opponent in combat. Players gain access to more advanced units upon construction of tech buildings and research. The majority of the display screen shows the part of the territory on which the player is currently operating, and, using the small minimap, the player can select another location to view and operate on. The fog of war completely hides all territory which the player has not explored: terrain that has been explored is always visible, but enemy units remain visible only so long as they stay within a friendly unit's visual radius.