Zones of control

Zones of Control (ZOC) is a game mechanic which in some cases prevents units from moving to tiles adjacent to enemy units.
== Purpose ==
ZOC enables the game to simulate the historical importance of tactical positioning and timing. Units who are timely in occupying a position first, gain an advantage in blocking/preventing or slowing/penalizing movement on newcomers to the tiles around them.
== Rules ==
👉🏽 The simplified general rule is explained first.
When ZOC is applicable, the general rule is fairly simple:
* A unit that is adjacent to a non-allied unit can't move directly to a tile adjacent to a non-allied unit.
** Occupied non-allied cities are assumed as having non-allied military units inside.
 
=== Cases where ZOC does not apply ===
* Only some types of units "impose ZOC". If the enemy unit is of a type which does not impose ZOC, the rule doesn't apply.
** In general, it is only military land-units who "impose ZOC".
* Only some types of units are "subject to ZOC". Other types move without blocking by ZOC rules.
** In general, it is only land units who are "subject to ZOC".
*** On land, there are "igZOC" units who ignore ZOC. For example, Explorers, Diplomats.
**Most or all non-land units are not subject to ZOC. For example, Aircraft, Missiles, Submarines, etc.
* If an enemy unit is in a base that makes it unseen, it does not impose ZOC. (1)
*The enemy unit does not impose ZOC if it stays on a non-ZOC terrain (in most rulesets, it's Oceanic).
**Transported units never impose ZOC. (2)
*The unit is moving directly into or out of a city.
* The unit is moving to a tile occupied and held by a friendly unit.
**Friendly "igZOC" units who ignore ZOC do not count when the server setting zoc_purity is enabled.
* A unit moving from or to a terrain-type not subject to ZOC rules (in most rulesets, it's ocean) .
== Graphical Example ==
==Notes:==
* Usually, only land units are restricted by ZOC.
* In some rulesets (and always in older versions), non-land units can impose ZOC, but only if they are on a land tile. 
**This means sea units can't impose ZOC unless they are in a city, river, or canal.
**Air units can't impose ZOC if they are over ocean squares.
* ZOC only restricts movement. It does not restrict attacks.
* An enemy city counts as an enemy occupied tile, but only if it's occupied.
* Moving from or to an ocean square is usually always allowed because ZOC is inactive on all ocean tiles. Also, boarding is always allowed because the allied unit you board is present in the tile.
*Some games may have the Freeciv Web server setting zoc_purity on, such as Multiplayer II rulesets. Read the link for more info how it changes the rules described on this page.
=== Annotations: ===
(1) A ruleset could in theory program certain extras on a tile to make any units there cause ZOC. (v3.3+)
(2) (unless playing an old Freeciv prior to v.3.0.8).
==Tip:==
You can infiltrate enemy zones by exploiting the rule that ZOC does not apply when moving onto a tile occupied by a friendly unit. Which units can do this will depend on the ruleset and the server's current zoc_purity setting.
Category:Terminology Category:Gameplay