In board wargames, zones of control (ZOC) represent the tiles adjacent to tiles occupied by objects. For example, in hexagonal tiled maps, the six hexagons adjacent to the hexagon occupied by a unit would be considered to be in its "zone of control."
Zones of control commonly are used to represent the portion of the map over which a military ground formation has a direct influence, due to the range of its weapons and the distance its sub-units may deploy from its center of gravity. Game rules often include specific effects associated with a zone of control. Typical effects include one or more of the following:
Zones of Control also represent the indirect effect a formation has on the movement rate of an enemy unit in its vicinity. That is, units deep behind friendly lines, and so outside enemy zones of control, may move almost at road speed under many conditions, while once they approach an enemy unit - and so enter its Zone of Control - their movement rate should slow dramatically, perhaps only to yards per hour, which in game terms is indistinguishable from stopping in the presence of the enemy.
Zones of control come in many forms, including fluid (sometimes called elastic), rigid and locking. Each type is judged by its effect on an enemy unit. For example, a fluid zone of control increases the movement cost of an enemy unit in its grasp (that is, it slows the enemy unit's speed); a rigid zone of control will force enemy units to stop and a locking zone of control will prevent an enemy unit from voluntarily leaving its position without combat. A zone of control may produce almost any combination of effects the game designer wishes.
Depending on what a designer is trying to represent, zones of control may be cancelled by terrain features such as mountains and rivers, by the presence of enemy units, or even by enemy zones of control.
Strategy computer games, such as the Civilization series, commonly use zones of control as a method to balance combat and grant extra strength to units in pairs.