11. Combat

Combat

A unit cannot enter a square occupied by an enemy unit, and when directed to do so will attack instead, locking the two units in combat until one is destroyed. An attack usually costs the aggressor two movement time, but results in no actual motion — the surviving unit remains where it was when the combat started. Bombers spend all of their remaining movement time when they attack, which gives fighters a chance to intercept them.

Some restrictions upon warfare are rather obvious — units must have a nonzero attack strength to attack, while defenders with zero defense strength lose immediately. There are also limits upon which units can attack which others. Land units can only attack other land units. Ships can attack not only other ships, but any land units adjacent to them (submarines are an exception and cannot attack land units). Helicopters can attack land and sea units and can be attacked by any kind of unit (land, sea, or air), at any time. Bombers and missiles can attack anything on land or sea, and though their targets will defend themselves from attack, they cannot attack the bomber in return. Only fighters can attack every kind of unit.

Note that aircraft within cities and air bases are on the ground, and thus vulnerable to land attack. Ships in port are similarly vulnerable. Note also the special ability of marines to attack targets from aboard ship; other land units must disembark before engaging enemy units.

There are two other actions related to combat. A unit ordered to sentry remains in place indefinitely and no longer asks for orders each turn. Sentry units can not only be reactivated manually (by selecting them), but activate automatically should an enemy unit come into view. Land units can additionally be ordered to fortify, once fortified they enjoy the same advantage as land units within an unwalled city (+25% defense bonus). A unit whose movement time are exhausted cannot fortify.

Combat Mechanics

Each unit begins combat with attack strength and accumulated time, which are the amount of damage it can sustain. In each round one unit succeeds in wounding the other.

The game engine calculates the attacker unit's attack bonuses: veteran level + offensive skill + attack bonuses of wonders; calculates the attacked unit's defense bonuses: veteran level + defensive skill + fortified bonus + city bonus + terrain's defense bonus + landscape's defense bonus + defense bonus of buildings + defense bonus of wonders; calculates the attack and defense points: attack strength * attack bonus and defense strength * defense bonus; decrease the health point of the attacked unit by the result of the attack points / defense points * gaussian randomness.

If the attacked unit has survived the attack, the game engine calculates the hit-back with half power.

Aftermath

Survived units have encounter one veteran point which gives them greater strength in all future engagements.

Units remain damaged after losing hit points in combat, and will enter subsequent engagements with this disadvantage. Damaged land and sea units also begin each movement with more movement time than normal, in proportion to what fraction of their total hit points remain. All units restores 20 points per hour if the unit is fortified and 4 points per hour otherwise.

If you sentry a damaged unit, it will become active again and demand further orders when its hit points are fully restored.

Cities and forts

When several units on the same square are attacked, the most appropriate unit (calculated by defense strength multiplied with health points) paired with the attacker unit. When a ship carrying other units is involved in combat (as either attacker or defender), only the ship participates in the engagement and its occupants are lost if the ship goes down.

Once the last defender has fallen you may enter the city kill one citizen if the attacker is a land unit and claim it as your own with either a land unit or helicopter;ships and aircraft can assault cities but not take them. Upon the capture of a city from another civilization, each building has a one-fifth chance of being destroyed, and the victor may discover a technology held by the vanquished.

Building a fortress requires the construction advance. To begin construction, move settlers, workers, or engineers to the location at which you desire a fort and give them the build fortress order. The work will require only three settler-turns. A fortress can stand anywhere outside of a city.

Nuclear

Nuclear missiles do not engage in combat like other units — they either strike within range of an SDI Defense and are harmlessly destroyed, or detonate and blast the entire 5x5 area centered on the unit or city they attack. Within the blast area all units are destroyed, cities lose half their population, and each land square has a one-half chance of becoming polluted with fallout.

Just as excessive pollution across the world can trigger global warming, fallout raises the chances of nuclear winter with the opposite effect — rather than coastlines becoming jungles and swamp, terrain begins changing into desert and tundra. Settlers, workers, and engineers must be given the clean fallout command to dispose of nuclear waste, which costs three settler-turns per square.

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