Construction

Drones are the Zerg resource harvesters and builders for the swarm. However, when ordered to make a building, the Drone itself will morph into the structure. Needless to say, a full base will require several Drones to make. It is a good idea to have plenty of Drones still gathering resources and to never use the last Drone to make a structure.

Expansion

Unlike other races, the Zerg cannot just build their structures anywhere they want. A Zerg base will have a purple goo growing around it called the Creep. Zerg structures can only be built upon this Creep, but a Hatchery may still be placed on open ground. The Creep can be expanded by constructing Creep Tumors. Hatcheries and Creep Tumors will uphold the Creep around itself and Overlords can be used to create Creep. If any of these structures are destroyed, the Creep will slowly begin to fade. Note that if the Creep fades away from any other Zerg buildings, those structures will begin slowly losing health until it is destroyed.

The Creep also provides a passive speed bonus to ground units. All units except the Drone will move 30% faster while they remain on the Creep. This bonus will still apply even if the Player is on Creep supported by an enemy base. Some units, such as the Queen, move significantly faster when they are on the Creep.

Recovery

The Zerg do not have any quick way to recover themselves, but they do rejuvenate. All Zerg units will recover 1 hit point every 3.6 seconds even while in combat. This means a unit with low health can recover back to full if given enough time. While this recover is pretty slow, the Queen does have an ability to heal injured Zerg units.

Hatchery

While the Hatchery is the primary starting structure and is used to gether resources from Drones, it also plays a key role in unit production. Hatcheries, Lairs, and Hives will generate Larva every 15 seconds while there are less than 3 Larva. Each of these structures can hold up to three Larva at any one time. Queens also have to ability to spawn additional Larva on a nearby Hatchery. The Larvae can morph into any of the various units in the Zerg strains once the proper building is made. Unlike other races which have multiple structures to build certain units, the Zerg can build their entire force from the Larva. When ordered to spawn into a particular unit, it will form into a defensive egg and begin morphing. After the morphing is complete the egg will hatch. Thus to build units faster, a Zerg player will need to build several Hatcheries or Queens. The advantage here is that the Zerg player can change the units they make without having to build extra factory structures like other races.

Nydus Network

The Nydus Network is a special underground Zerg transport that can instantly move units to another part of the map. When this structure is created, it has the ability to build Nydus Worms that act as a travel route for the swarm. A Nydus Network can have multiple Nydus Worms constructed. It is possible to construct a worm on a hostile base, but the Player must see the area. When a Nydus Worm is constructed, it will make a loud screaming noise that can be heard by all players alerting them that the Zerg are moving underground.

Up to 255 units can be stored in the Nydus Network and can be unloaded at any Nydus Worm on demand. If the Nydus Network and all Nydus Worms happen to be destroyed, then all units stored in the network are lost. Allied units cannot be loaded into a Nydus Network nor can the Spine and Spore Crawlers.

The zerg are a race entirely unlike the terrans or the protoss. They are composed of many different species integrated into the Swarm via zerg infestation. These creatures are rapidly and selectively evolved into deadly and efficient killers to further the driving zerg imperative of achieving absolute domination. The zerg make no use of technology to create their weapons, armor, or starships. Instead, these functions are efficiently fulfilled through biological adaptation and planned mutation of the zerg strains. Even zerg buildings are in fact specialized organs within the living, growing organism of a zerg nest.

When the zerg first arrived in the Koprulu sector, they were unified by their absolute obedience to the zerg collective sentience known as the Overmind. The Overmind ultimately directed the actions of every zerg creature in the Swarm, functioning through a hierarchy of lesser sentiences. The first and most important tier of these consisted of the cerebrates, each entrusted with direct control of a sizable section of the Swarm. The cerebrates' commands were disseminated in turn by the overlords, which directly ordered and controlled the mass of zerg creatures both in their nests and on the battlefield.

Although the Overmind was primarily driven by its desire to consume and assimilate the advanced protoss race, it found useful but undeveloped material in humanity. Taking a powerful terran psionic, Sarah Kerrigan, the Overmind evolved a new and unique creature: the Queen of Blades. When the protoss destroyed the Overmind during the invasion of Aiur, the Queen of Blades manipulated the dark templar into eliminating the surviving cerebrates. As a result, she came to dominate the Swarm.