Target selection

The first actual combat step is the selection of targets. Each weapon on a ship or building may select a different target; while this may at first look like it makes no sense (and in the case of e.g. fighters, it is quite true), it is extremely important for bigger ships – if weapons fire was concentrated on a single ship, most of it would be wasted.

Target selection needs to be executed when a weapon has no target, when its target has been destroyed or when a mode switched occurred and the previous target should no longer be fired upon. In addition, depending on the fleet’s current strategy, there is a probability of spontaneously changing targets (for planet-based weapons, this probability is fixed to a relatively low value – 5% in the latest tests, but it may change a lot before the milestone’s release). If there is no need for a new target, then the target selection step is skipped.

At this point, all potential targets are examined. A weight is assigned to each target depending on the fleet’s (or planet’s) tactics settings:

• size-based selection, giving priority to either smaller, bigger or similarly-sized ships (buildings are considered to be medium sized),
• selection based on weapon power, giving priority to either more powerful, less powerful or similarly powerful ships or buildings,
• selection based on countermeasures, giving priority to either the most armoured ships, the least armoured ships, or similarly defended ships (buildings are never armoured in this version).

If the weapon is on an attacking ship, the weight of each target is then modified depending on the fleet’s attack strategy. This includes giving more or less weight to military ground structures and civilian ground structures.

Finally, a target is selected at random, with higher-weight potential targets being more likely to be selected than lower-weight targets.

Weapons firing

Once their target has been selected, weapons that are ready to fire will do so. The probability of success, and therefore various data such as the weapon’s damage or the probability of interception, depend on a set of variables.

• The probability of firing accurately is computed from the weapon’s accuracy, modified by the ship’s experience (buildings do not get experience points).
• The target’s manoeuvrability, modified by its experience, is used by the target to try and escape the shot. Of course, since buildings do not move, they do not escape shots.
• An “advantage” index is then computed, based on: the hit points of both the target and the weapon’s platform, the manoeuvrability of the weapon’s platform, and a modifier that depends on the relative strategies of the fleets (planets do not have a strategy, so the aim modifier of planets versus attack fleets and vice-versa are part of the attack strategy itself).

A bit of randomisation is then introduced, and a success index is computed. This index may indicate that the shot missed, or that it would hit but could be intercepted, or that it will hit. If the shot is successful, the damage it would inflict is then computed. It is based on the weapon’s base damage, and modified by the shot’s success index. It may be increased or damped depending on the fleets’ relative strategies. In addition, really successful shots will be considered “critical”, which will double their damage (the exact multiplier for critical shots may still change).

Interception

It is possible for a fleet’s ships to intercept shots aimed at other fleets, or at the planet if they are defending. When a shot is intercepted, the ship that intercepted it will take the damage instead of the intended target. Strategies which include a high interception probability may for example be used to provide cover for other, more powerful ships.

The probability of a ship intercepting a shot is determined by the fleet’s strategy, by various modifiers (current ship “health”, experience, manoeuvrability), by the amount of shots aimed at the fleet itself (a ship busy trying to escape shots is less likely to intercept a shot aimed at someone else) and of course by how successful the attack was. A ship may only intercept a single shot at each minute.

A note on strategies

As this post shows, strategies define a lot of modifiers applied to ships and planets during combat. A limited number of attack and defence strategies will be provided. Each strategy will have strong points, while being weaker on others. Strategy combinations are important too, as a strategy may be very efficient against another but very weak against a third. In addition, strategies are also involved in the ground combat computation; more details about that will be provided in the next post.

There are two major computations performed by the battle system. First, space combat is computed. Once this part is over, and provided there are still attacking ships in orbit, computations regarding ground combat are performed. Once these two main chunks have been computed, experience points are attributed.

This posts attempts to explain what the various steps of each computation are and how they work, generally speaking.

This flowchart shows the essential steps of the battle computations. Exit conditions and various internal steps have been omitted for clarity.

Space combat

The first step of space combat is fleet updates. When attacking fleets first start a battle or when fleets join an ongoing battle, they suffer “time dilation” which causes them to be less efficient for some time. This time dilation effect must be decreased over time.

Once fleets’ time dilation strengths have been updated, ships need to undergo various systematic updates: ships that can repair themselves will regain hit points, countermeasures will recover from previous damage absorption, and weapons will charge or cool down. If no weapons are ready to fire, then the space combat computation is over.

If there are weapons ready to fire, the first step is target selection. If a weapon already has a target, there’s a chance it might still select another target – this depends on a fleet’s strategy (for planet-based weapon platforms, there is a fixed, very small probability of target change). If such a change needs to occur, or if the weapon had no target for some other reason, it will seek a target based on the fleet’s (or the planet’s) tactics – basically, it can select targets by size, weaponry or defences, with different priorities. An attacking fleet’s strategy will determine whether the weapon may target the planet’s infrastructure.

Once weapons have selected their targets, they may fire. A computation is performed to determine whether the weapon actually hits, whether the shot may be intercepted and which amount of damage it would cause on a “naked” ship from various variables such as the ship’s experience, current hit points, manoeuvrability… When a weapon fires, there’s also a small chance of a critical hit, which cannot be intercepted and deals twice as much damage.

Depending on strategy settings, some ships may try to intercept shots aimed at other fleets or at the planet. Such an interception depends on how successful the aim was, and on various other factors such as how many hits the intercepting fleet might sustain. A successful intercept will cause the ship that intercepted the shot to take the damage – which is particularly useful to defend planets. No ship can intercept two shots in a single battle update, however.

Once the destination of all shots have been computed, the corresponding damage is inflicted to ships and buildings. Ships may have countermeasures which can sometimes absorb part or totality of the damage. Of course, should a ship or building reach 0 hit points, it is destroyed. In addition, any ships or buildings that provide ground armies will have their army strength reduced accordingly.

Ground combat

Once space combat has been resolved, and provided there are any attacking ships left, the computation of ground combat begins.

First, the ground defence advantage is computed. It is determined by the amount and type of ships supporting ground troupes, by the amount and type of military buildings, and by the population’s happiness.

The support that fleets provide for ground armies may vary depending on a fleet’s current strategy. Fleet strategy also determines whether ships that carry armies should drop the troupes to the planet’s surface or attempt to extract them.

Once the system knows which armies are on the planet, providing there are both attacking and defending armies, ground combat is computed. The damage dealt by either side is mostly determined by the advantage value, although their respective sizes has an influence. Finally, damage is applied to armies (and to the corresponding ships or buildings).

Assigning experience points

After all actual fighting has been computed, experience points are given to ships (buildings will have no XP in milestone 2, but that might change later). The amount of experience points granted to a ship is determined by the damage it inflicted to other ships, by the shots it intercepted, and by the damage the ground armies it carries inflicted.

Next time…

… I will explain the mechanics of space combat more precisely, and how it is affected by fleet tactics and strategies.