This page is a work in progress. Assume that nothing described here is finalised yet and everything could work completely different in the end.

Current state and Goal

Fighting in 0 A.D. should be diverse, interesting and challenging. Good tactics should make it possible for a player with a smaller and weaker army to win against a stronger opponent. There should be multiple gameplay mechanics that enable the players to use a variety of tactics and to counter tactics of their opponents. Formations are a core element of battles, but there's currently just a placeholder implementation which does not have a real impact on how battles work in the game.

Battalions vs Single units

Currently, all units in 0 A.D. are controlled individually. A battalion is a new concept where units can only be selected and moved as a group. Battalions can be put into a formation.

Training

Approach A: Single units only

All units can by trained, selected and ordered individually. For fighting, you usually use a formation because that brings many tactical advantages and bonuses. This has some advantages compared to battalions:

• Garrisoning still works as designed. It would have to be redesigned for the battalion approach because the number of units in a battalion would exceed the room in some buildings.
• The battalion system would cause some inconsistencies that don't occur here because it was designed that way from the beginning. A few examples:
  • How would it work with female citizens in a battalion-only system? Are they also built in batches and how many units would be in such a batch?
  • How do you show which units are part of the same battalion? While collecting resources, the individual units could get separated a lot.
  • When defining the size of a battalion, do we really want to depend on the economic factors too in addition to the military ones? For example, we would like a large battalion to make the formations work, be we want a small one for economic reasons.
  • How much space for units is there around the different resource types (mines, forests, hunting, berries, fields etc.)?
  • We could still support mixing of different unit types in a formation if we want that.

On top of that, most of the disadvantages can be mitigated:

• The town bell takes away micor-management for garrisoning units and sending them back to work.
• There could be a shortcut and/or a button to select only wounded units
• Fighting happens in formations mostly, so the problem is solved on that part

Approach B: Battalions only

Units are trained in battalions already and they can't be separated. With a population cap of 300, it becomes quite a task to manage all the units individually. Such management tasks include:

• Splitting units to collect different resources
• Healing units or filtering out the insured units
• Garrisoning units when the base gets attacked and sending the back to work afterwards

Training all units in battalions reduces the tedious micro-management tasks and gives the player more time to do fun things.

Decision

Approach A will be used. It seems like Approach B only looks good in the beginning, but there are too many inconsistencies with how the game is designed and it would require too much changes for only little benefit.

Fighting

If we support fighting in formation as well as fighting as individual units, both need to be valid choices under some circumstances.

Fighting as individual units

• Garrisoning
• Raiding. A single formation is not mobile enough to run after individual units.

Fighting with formations

• Basically all other fighting

Number of units in formations

• There is a minimum number of units for each formation.
• There is a maximum number of units for each formation.
• You get the same formation bonus irrespective of the formation size.
• Morale: The panic-effect on other battalions is smaller for smaller battalions
• Morale: You need to kill the same percentage of units in the same amount of time for all sizes of formations to cause panic-mode (assuming no other effects on morale).

Unit types and formations

We need a decision how we restrict the type of units that can form a formation together.

Allowing ranged and melee mix

TODO

Forming and disbanding a formation

Forming a formation

A formation is formed by selecting a number of units and clicking the button of the desired formation. Buttons only become active when all requirements are met. For example, a formation requires a minimum number of units or it requires units of a specific type.

TODO

Disbanding a formation

TODO

Fighting in formation

Default behaviour (melee)

• Units stay in formation until they are very close to an enemy.
• When the first unit in the formation starts fighting, the other units attack too.
• The first row of the formation moves forward until they are close enough to attack.
• Units try to keep their flanks protected, meaning that the first row will stay connected during attack, but it will not stay a straight line unless the two fighting formations attack perfectly frontal.
• Rows after the first one follow the units in front of them
• When a unit in the first row dies, units from behind catch up

Ranged

TODO

Special behaviour

There are some special formations that might need to stay in formation more strictly (TODO).

Movement in formation

Formations have a larger obstruction than single units and have difficulties pathing through narrow gaps. The following approach is used to work around this issue.

• When you issue a move order to a formation, the formation behaves differently depending on the distance from the destination
• For a short distance it tries to move in formation and will query the pathfinder for the larger obstruction size.
• If the distance is longer or if no path could be found with the large obstruction size of the formation, the units will change to column formation for the movement.
• When moving in column formation, the units will re-establish the original formation when they are close enough to the target

TODO: Some open questions:

• How wide is the column for movement? It looks weird if the column is too narrow, but anything wider increases the risk that no path can be found.
• How does the formation choose between shorter paths that require a more narrow column or longer paths that allow movement in a wider column. Can it switch to a more narrow column somewhere in the middle of the path?

Formation positioning

You click to the spot where the left side of the formation should be placed and then drag your mouse to the right side. Going further right means your formation will have more columns but less rows. Clicking to the right and moving the mouse to the left on the screen will do the same, but the formation will be turned 180 degree (so the left side with respect to the formation is always where you start click-dragging the mouse). Some formations may have a limitation how many rows or columns they need as a minimum. Such restrictions will be reflected in a preview while you are dragging the mouse.

Directionality

So far, formations basically just reduce the number of entities the player has to control and therefore make it possible to use the rock/paper/scissors concept. To offer real tactical depth for battles, we need some other means of getting an advantage over the enemy.

Formation based

Directionality for formations means that formations have an orientation and units get different modifications for their attack and/or defense values based on the direction they are facing relative to the formatin orientation. This can be used to achieve two slightly different mechanics:

1. Surrounding

Assuming a formation can change its orientation nearly instantly, the only way to take advantage of directionality is to attack from more than one sides. The formation can turn quickly, but it can't face two directions at the same time. It also feels quite apparent that surrounding troops or attacking them from two sides should give you some advantage and therefore the concept can be easily explained to players.

1. Outmaneuvering

If formations have a limitation how far they can turn, there's also the possibility of outmaneuvering slow formations. This could be applied to special formations like a Phalanx, which is very deadly against chavalry when attacked from the front but vulnerable when attacked from the back.

Unit based

Unit based directionality means that a unit has weaker armor on the back and the sides. If you attack a formation from the side, the units there will obviously turn to face the attackers. They have their defense values reduced because they are on the side of the formation (formation directionality), but their defense values aren't reduced further because the unit itself faces the attacker (unit directionality). Unit based directionality applies in the following situations:

1. Attacking units on formation-corners

If you manage to attack a unit at the corner of a formation from the front and the side, you can benefit from unit based directionality. To prevent this, players want to close gaps between formations or make their formation wider than the enemy formation. If the attacker manages to break the line completely, this effectively doubles the number of corners and opens a way to get behind the formation.

2. Wide formation with few ranks

As described above, formation directionality favors very wide formations to make it harder for the enemy to attack them from the side or from behind and to keep the corners protected. With unit directionality added, wide formations get more disadvantages. If the formation is so thin that you can not just attack the formation from behind, but also the units, the attacker get both bonuses. Unit attack range will have to be fine-tuned for this effect to work. It might be good if at least some units could reach further than one rank in the formation so that you also get a unit directionality bonus when attacking a formation which is two ranks deep.

Formation bonuses

Different types of formations give different modifications to unit properties (attack, defense, move speed etc.). There can be positive and negative modifications and modifications can be directional (see directionality) or general.

Morale

• Winning without killing all enemies (adding more depth to a battle by offering another way to victory)
• Good for auras (Heros to boost morale, some units that scare the enemy and reduce their morale)
• Interesting for technology choices: boost attack and defense or morale?
• Morale is calculated per battalion
• When a formation is disbanded, all units take over the morale value of the formation (the percentage). This prevents that players quickly disband and then form a battalion again to refresh the morale. It's still possible to mix units with low and high morale to get a battalion with a morale value somewhere in the middle, but that's probably fine.

What influences morale?

• Positive auras. Example: Hero colse
• Negative auras. Example: Enemy elephant attacking reduces morale regeneration rate
• Experienced troops have increased morale
• Heavily armored champion units have more morale. TODO: More armor effectively means more morale already because units die slower. Do they really need more total morale in addition? Maybe yes, because that makes them more resistant to the other effects on morale.
• Loss of units: The key here is that a dying unit reduces the morale points by more than the total number of points divided by the number of units. This means that a short and strong attack has a large impact on morale but a relatively low impact on the number of units in the battalion.
• Morale automatically regenerates slowly. Regeneration is faster when the battalion is not in battle (Not in battle meansing something like: "not attacked since x seconds" or "total attack in the last 10 seconds smaller than X points")
• The battalion has a range. If another allied battalion within that range changes to panic mode, this also reduces the morale of the current battalion. This can cause a cascade effect which make the tactic of winning a battle by destroying the enemy morale stronger (this can be balanced by increasing or reducing the effect).

What happens if morale reaches 0?

• The formation changes to panic mode
• This is indicated in some way (changed battalion banner, panic-animations playing for units from time to time, sound effects etc.)
• Units in panic mode have reduced attack and armor values. They play the panic-animation from time to time and don't fight while doing that.
• A formation in panic mode is so weak that it has to be pulled back from battle
• Units are still grouped
• Units keep their current positions, but they change to a panic mode formation (basically random grouping of units) which takes effect when the units are moved.
• Battalions in panic mode can't be disbanded
• Units recover from panic mode when their morale raises above 50% again (value to be adjusted during playtesting and balancing)

Tactical considerations

• If a formation presets a larger front to the enemy, it inflicts more damage but is also more vulnerable to loosing morale. You might want to use a different formation layout depending on how strong the morale of your units is and how easily you can retreat them. For example, if you are fighting a battle in front of your own gates, you might want to quickly deal a lot of damage to the enemy troops and then retreat your panicing troops behind the walls.

Stamina

The question is if we actually need stamina in addition to morale because they are similar.

Brainstorming...

• Differentiate between light units that can move faster and further with their stamina and heavy units that can fight longer (different stamina use for movement and fighting)
• Practically increase the distance between settlements without requiring larger maps (movement takes stamina)
• Adding another aspect to battle. If you had a long march and then immediately start fighting, you have a disadvantage because of stamina

Charging

TODO