Horde

## Overview

A group of infected acting towards the same stimulus is known as a horde. It is not exactly a certain number of infected that classifies a group of infected as a horde, but rather the ***behavior*** of the collective infected that makes a horde truly a horde. Individual infected are generally very unintelligent, but are prone to mirroring other infected's behavior. Common infected in particular are easily influenced by other infected's actions. Where one infected goes, another may follow. Where 10 go, more are sure to take interest. Where 50 go, countless more will join. A few members of a horde may attempt to break down a door. The others will see this and join in. Some infected in a horde may wander off in a random direction. The rest of the horde may begin to follow them, and now the horde has become mobile. A horde will usually wander aimlessly, destroying everything in their path, until potential prey is spotted or another stimulus, such as a loud noise like a car alarm, gathers their attention. The more infected are present in a horde, the more capable and focused each individual infected becomes - essentially creating a positive feedback loop that is difficult to break. Hordes are a self-sustaining force of destruction that rarely dissolve by themselves and instead tend to continue to grow and grow like a terrible plague.

## Gameplay

### Horde formation:

Horde behavior is usually only seen with walkers and runners. In this regard, hordes are generally only comprised of common infected. Mutant infected may sometimes be present in a horde, but usually do not form hordes of other mutants. Hordes can prove a deadly obstacle in many situations, and with the appearance of a horde come new rules in dealing with the massed infected.

Hordes are usually spawned into the world (most often for scripted encounters and events), but they can naturally form over time in the open world by individual infected collecting into a group. A single infected begins acting out - barking at the air, moving with purpose, and swiveling their head quickly in different directions. Other infected will see this and approach the infected and begin to vibrate with excitement. Once this group has grown to a significant number (usually 10+ infected), they now become a horde and their behavior radically changes. It is usually wandering infected that collect into hordes - idle walkers are generally uninterested in joining hordes, but should a horde become rowdy enough, it may rouse even the most apathetic of infected into joining. An on-screen cue is usually displayed to warn the player that a horde is forming. This cue is only shown when observing a group of common infected for long enough. Also, hordes being nearby or forming nearby are signified by an auditory cue as well - a loud collection of deathly groans. Thus, observation and scouting tactics become important in detecting hordes before they can form.

A horde can form instantaneously. Noisy areas are more prone to collecting infected and forming hordes. For example: places where car alarms or an emergency vehicle's siren have gone off, or places where firefights have erupted or prolonged shooting in general has happened. Leaving an area after creating a loud noise is not enough - oftentimes, one will return to an area to see it has been completely overrun by a new horde that has spawned while they were gone. Besides noise, hordes will also just form by themselves if the local infected population hasn't been controlled. If an area has been effectively cleared of infected, then hordes are less likely to form or spawn there. An area that is infested with infected may become a horde factory - producing wandering hordes left and right that will run rampant throughout the map. These areas are especially problematic.

### Horde behavior:

When a horde has formed, one may notice that infected become less likely to act individually, and will begin to function as a unit. This means that attracting the attention of one member of a horde is almost guaranteed to alert the rest. This makes it extremely difficult to fight a horde in melee, as one would be fighting every infected in a horde at once, instead of one by one. Additionally, the stats of each individual infected in a horde is boosted - horde walkers are slightly faster, stronger, and tougher. They also attack more aggressively and noisily.

Barricades that are usually impenetrable to lone infected or a few infected may be smashed through within seconds by horde-numbers of infected, due to the exponential damage to barricades that larger numbers of infected deal. Hordes are especially dangerous to safehouses and survivor hubs because of this reason. However, the strongest of barricades that transform a passageway into a wall, like stacks of sandbags or bricks, remain impassable because they do not even look like passageways to infected anymore.

### Stationary vs. Wandering hordes:

Stationary hordes are less of a threat than a moving horde, but they can be troublesome if they are in the way of a mission objective or are inhabiting an area that needs to be passed through. Stationary hordes can block roads or other passageways, causing a great deal of annoyance and danger. Worse still, stationary hordes can suddenly become a wandering horde at any time if a strong enough stimulus is present. Wandering hordes will generally travel around the map in random directions with no intended destination, but their direction and path of travel may be altered by loud noises such as distant gunfire.

### Horde attacks:

The path of a wandering horde will sometimes align with survivor hubs or other safehouses and they will lay siege to them relentlessly until the horde is destroyed. These "horde attack" events can cause severe damage to barricades, injure or kill many survivors, and in extreme cases, cause the loss of a safehouse due to it being overrun by infected. Being in a safehouse or survivor hub when a horde attack event is imminent is usually indicated by a number of signs:

* Some survivors will comment anxiously that a horde is approaching and warn the others to prepare their weapons and get into position
* Sound cues and music changes accompany the approach of a horde
* A horde that has been detected by the player character already will appear on the minimap as an icon that is now flashing as it gets closer, accompanied by a "Horde attack!" HUD element
* When the horde gets near, the terrible roars of countless infected can be heard.

Horde attacks, if survived, can offer great boosts to EXP. The more horde infected that are killed during an attack, the more EXP given.

Hordes that have been detected by the player or allied NPC will be marked on the world map with an icon. These icons only show the ***last*** location a horde was seen in. If a horde begins moving, these icons no longer become accurate for pinpointing horde locations. On the minimap, however, the icon of a spotted horde will remain. One can use this to visualize where a horde is moving, and plan accordingly.

## Strategy

* Hordes are noisy - hearing an agglomeration of noisy groans can tell you that a horde is nearby without even having to see it.
* To stop a horde that is forming in front of the player character, one must pinpoint the "initiator", the particularly energetic infected that is barking at the air and moving with extra energy. Killing this infected will probably attract the many others near it, but they will not have formed horde-behavior yet, so they will each be much easier to dispatch.
* Stationary hordes can be moved from their location by using distractions - or simply gaining their attention, having them chase you, and then losing their attention when they are far enough away. However, this method carries the risk of turning the stationary horde into a wandering one.
* Hordes are notoriously difficult to break up once formed, but using distractions in several different directions may succeed in breaking a horde up. Additionally, recruited survivors can be tasked with horde dispersal, which is safer than combating the horde head-on.
* Ramming into smaller hordes of walkers with vehicles is a valid method of eliminating them, but be warned that most vehicles can get stuck on walker bodies and gore.
* Heavy machine gun emplacements are extremely effective at eliminating hordes due to their power and high rate of fire. Ammunition can be scarce, however, so save these powerful weapons for emergencies.