- Low cost per unit produced
- Low unit power
- Low control consumption per unit
- Unmatched ability to swarm ('zerg') an opponent
- All zerg units (and buildings) regenerate their health points over time. Therefore, unless all units and structures are completely eradicated, the hive colony will not be destroyed as the structures and units, even ones that are on the verge of death, will return to full health. All zerg ground units can be healed by allied terran medics (Brood War only).
- Most of the land units (with ultralisks and broodlings being the only exceptions) have the unique "burrow" ability; this is a very effective way to set up an ambush. Burrowed units can only be harmed by area-of-effect attacks such as psionic storm and siege tanks in siege mode, unless they are revealed by a detector unit. However, burrowed units cannot attack, move or use special abilities. The only exception is the lurker (Brood War only), which can attack only when burrowed. Burrowed zerglings spread throughout the map provide a very cheap and effective method for following enemy troop movements.
- Least efficient building method (the drone becomes a building), extreme building restrictions. Zerg structures can only be built on the creep. The creep is formed by a hatchery (zerg's main structure) and can be extended by a creep colony. Only the hatchery and extractor have no building restrictions, as creep colonies must be built upon existing creep themselves. Certain buildings must be 'upgraded' to attain higher technology level.
- Many zerg units (except broodlings, lurkers, infested terrans, devourers, and guardians, most of which are directly morphed from more basic units) are made from larvae at the hatchery. This allows zerg to quickly switch unit combinations, counteracting the high building cost. It also allows for more parallel production than the other races, allowing large numbers of units to be produced in short order if necessary/possible, without as much required infrastructure. A good example: 4 terran barracks will produces 4 marines simultaneously, while 4 hatcheries can produce 12 hydralisks simultaneously. If a terran player now wants siege tanks at the same speed, he must now build four separate terran factories and their addons, while if the zerg player wants ultralisks, all he needs to do is build a single ultralisk cavern. Production will not be hampered on the zerg's side, simultaneously pumping out 12 ultralisks.
- The toughest aspect of zerg is generally thought to be knowing when to use your larvae to build more drones (in order to strengthen your economy for the long term) vs. when to use them to make more units (for defense and offense in the short term).
- Consume, a defiler special ability. It destroys a targeted unit of your own army and partly restores the energy (50 energy points regardless of the consumed unit) (required to use special abilities) of the caster. Because of the very low unit cost (particularly for zerglings), the defilers can recharge instantly almost for free. Other races must wait for the energy to replenish over time.
- Spawn Broodling, a queen special ability. It destroys the targeted organic or mechanical unit almost instantly and creates small, very low-health units called broodlings that are used mainly for scouting or harassment purposes (and to add insult to injury). Typically used to destroy deployed terran siege tanks or protoss high templar.
- Plague, a defiler special ability. It reduces the affected unit's HP by 300 hit points or down to 1 hit point, whichever comes first. It can be very useful against grand fleets of battlecruisers and carriers, or against terran or protoss bases.
Units and Buildings
All zerg units slowly heal over time, and all zerg ground units (except for the ultralisk and broodling) have the ability to burrow once the evolution is researched (but lurkers have it even if it is not researched). All zerg units are morphed from larvae produced at the hatchery, lair, or hive.
- Larva — tiny unit spawned from a hatchery, lair, or hive. Up to three are spawned over time. They carry the genetic makeup required for each zerg unit (except broodlings, lurkers, infested terrans, devourers, and guardians: see below), but a young hive cluster will only have the genetic code for the most basic of zerg breeds. They have low hit points and you cannot control their movement, but an extremely thick carapace absorbs a lot of the damage inflicted upon them. When ordered to morph into a unit, they transform into an "egg" until the units hatch. Eggs are nearly impervious to attack as they have high hit points and an extremely thick carapace. One unit is hatched from it, except in the case of zerglings and scourge, whose genetic simplicity allows two to hatch from each egg. Larvae eventually die when they are cut off from the creep.
- Drone — worker, consumed when creating a new base structure. Has a weak attack that cannot be upgraded.
- Zergling — melee attackers, the weakest of the basic ground units, but very low-cost, as a single egg hatches two zerglings; the "Adrenal Glands" upgrade available at hive tech level gives them a considerable increase in attack speed. Movement upgrade is also available. Zerglings' power must not be underestimated; it is easy to quickly produce huge amounts of them, and when fully upgraded, their sheer numbers can overwhelm an opponent quickly. Requires spawning pool.
- Hydralisk — distance attack. Generally regarded as the most versatile unit, masses of hydralisks can defeat almost anything (especially when used in conjunction with Dark Swarm). Hydralisks are the only zerg ground units that can attack air units, so they are essential in any game. Many people feel that hydralisks are one of most cost-efficient units in the game. Hydralisks are quickly dispatched by Psi Storms and siege tanks. Movement and attack range upgrade available. Requires hydralisk den.
- Lurker — morphs from hydralisk. Must burrow to attack, but is invisible to opponents, except for detectors. The ranged ground attack is especially damaging to small-sized units, such as terran infantry. Splash damage is linear and does not decrease with distance or position. Consumes twice as many supply points as hydralisk. It is vulnerable to the air units. Requires "Lurker Aspect" evolution at the hydralisk den. (Brood War only)
- Defiler — caster, no non-special ability attack. Have 3 types of special abilities: consume, dark swarm and plague. Consume sacrifices a player controlled zerg land unit for 50 energy points for the defiler regardless of the unit sacrificed. Dark Swarm is a temporary area effect special ability that negates all ranged attack that falls within the dark swarm — only melee and splash damage can affect health points. Dark Swarm tends to be the defiler's most useful special ability. In the hands of an expert, it allows a small group of hydralisks or zerglings to destroy far superior forces. Plague is a very lethal special ability, reducing the affected units or structures HP by 300 or down to 1 hit point, whichever comes first. It is very useful against fleets of battlecruisers and carriers as well as enemy bases. Special ability and energy point upgrades must be researched before use (dark swarm is the only inherent special ability). Requires defiler mound.
- Ultralisk — expensive heavy melee unit. It is not efficient as an attacker and is better used to absorb enemy fire. In Brood War, it receives and armor and speed upgrade that dramatically improves its effectiveness. Requires ultralisk cavern.
- Broodling — special unit, see "Spawn Broodling" in general attributes above. Spawned by the death of a land unit when affected by a zerg queen's Spawn Broodling special ability. All broodlings will die eventually regardless of health about two minutes from the time they were created.
- Infested Terran — special unit (see "queen" below). Is manufactured from a previously infested terran command center. It is a kamikaze unit that has attack power with a damage equivalent to that of a nuke, but, with a smaller area of effect. The unit can destroy any land unit in one hit.
- Overlord — supply, detector, and (when upgraded), transport unit. Although initially very slow, an upgrade available at the lair can increase its speed to a reasonable level. There is also the ability to upgrade its sight range, making it into a very effective scouting unit. An evolution available at the lair gives it the ability to transport up to eight unit slots (each unit takes up a different number of slots; zerglings, broodlings, and drones take up one slot, hydralisks and defilers take up two, and ultralisks and lurkers take up four). It is capable of detecting cloaked and burrowed units. However, the overlord is incapable of attacking, making it easily vulnerable to enemy units. In the late game, overlords are very cost effective units for the zerg, as they provide supply, detection, and transportation for a price considerably lower than the protoss and terran equivalents.
- Mutalisk — short-range air and ground attack attack. Bounces three times for reduced damage in each successive attack. However they are fast and their light armor status renders them highly resistant to many explosive anti-air defenses. They are not cost effective unless used in large groups and against units incapable of attacking air targets or units with a slow firing rate. Mutalisks are often used to harass the opponent's harvester units. Base unit for devourer and guardian. Requires a spire.
- Guardian — can only attack ground targets. Morphs from mutalisk. It has a long-range attack, capable of destroying all stationary defenses without fear of retaliation (but they must watch out for terran goliaths with upgraded range). However, they are painfully slow and must be backed up by units capable of defending against air targets. This is the main zerg artillery (siege) unit. Requires a greater spire.
- Devourer — can only attack air units, with a slow attack speed. However, its attack is incredibly devastating. For each acid spore that a unit is hit with (up to 9), the firing rate is slowed and the unit takes additional damage from all attack until they wear off. Also morphs from mutalisk, but moves much faster than guardians. Requires a greater spire. (Brood War only)
- Scourge — blind kamikaze unit. Capable of kamikaze of air units through a plasma metamorphosis. Powerful attack that is necessary for bringing down a large force of terran battlecruisers or protoss carriers. Is useful for stopping drops and destroying isolated air units. Low hit points. Like the zergling, the DNA of the scourge are so simple that two are hatched from every egg. Requires a spire.
- Queen — caster, no non-special ability attack. Special abilities: "parasite" enables you to see what the infected unit sees, including detecting ability — can be negated by the medic's restore special ability (Brood War only) — inherent special ability (no special ability upgraded needed); "ensnare" is an area effect special ability that slows enemy unit attack and movement rates. It also reveals cloaked (but not burrowed, which includes mines and traps) units affected by it; "Spawn Broodling" instantly kills a land unit to create two low-hit point broodling units. Also, the queen has the ability to Infest a heavily damaged (750 health and below) terran command center and transform it into a factory of infested terrans. Requires queen's nest.
Zerg structures are unique in two major ways. First, zerg structures are considered alive and heal over time, just as zerg units do, and bleed when injured. Also, all zerg structures except for the hatchery and extractor (which is restricted to construction over a vespene geyser) must be built on a thick, spongy purplish-brown material known as the creep. Creep colonies are needed to extend the creep to allow the manifestation of other zerg structures. When a creep colony, sunken colony, spore colony, hatchery, lair, or hive is destroyed, all corresponding creep retreats except for a tiny area around other structures. Larvae eventually die when not sustained by the creep. Structures of other races may not be built on the creep, but will not be destroyed when overrun by it. The exception to this are the structures of other zerg — in fact, a common zerg/zerg tactic is to open a nydus canal to the opponent's creep and deploy troops right into his or her base.
- Hatchery (Primary Larva Spawning Grounds/Resource Metabolizer) — spawns larvae from which to morph zerg units (up to three). Also allows the burrow evolution, which allow all ground units (except for the ultralisk and broodling) to burrow into the ground at will. Only zerg building without any building constraints (except for the usual resources restraint), and also expands the creep further. Provides limited supply.
- Evolution chamber — provides three levels of upgrades for zerg ground unit attack power and armor (attack power of drone is not upgraded).
- Spawning pool — allows for the construction of zerglings at the hatchery. Contains upgrades for the movement speed and (once you have a Hive) attack speed of zerglings. Requires a hatchery.
- Creep colony — expands the creep. Can be upgraded to spore or sunken colony.
- Spore Colony — stationary defensive structure capable of attacking air units with rapid-fire spores. Can detect cloaked and burrowed units. More resilient than other defenses but weak to ground foes. Requires an evolution chamber.
- Sunken colony — stationary defensive structure capable of attacking ground units. High damage, compared to other defenses, however it is unable to detect hidden units nor attack aircraft. Requires a spawning pool.
- Hydralisk den — allows for the morphing of hydralisks. Contains speed and attack range upgrades for the hydralisk, as well as the "Lurker Aspect" (Brood War only; requires Lair), which allows for the morphing of lurkers. Requires a spawning pool.
- Lair — upgrade of hatchery. Required for second level of Evolution Chamber upgrades, some advanced structures, and the Lurker Aspect at the hydralisk den. Carries over all abilities of a hatchery, but with increased hit points. Also allows for the sight range and speed upgrades for overlords, as well as the transporting evolution. Requires a spawning pool.
- Spire — grants ability to morph mutalisks and scourge. Also contains upgrades to armor and attack power for air units (attack power of scourge is not upgraded). Requires a lair.
- Queen's nest — required for morphing of queens. Allows evolution of ensnare and spawn broodling ability for queens, as well as an energy upgrade. Required for hive.
- Hive (Advanced Lair) — upgrade of lair. Retains all the abilities of a lair, as well as allowing for the third-level armor and weapon upgrades at the spire, greater spire, and evolution chamber and the rest of the structures (and the attack speed upgrade for zerglings at the spawning pool). Requires queen's nest.
- Nydus canal — ability to instantly transport ground units from one location to another (and back). The "exit" location can only be constructed on creep. Requires hive.
- Defiler mound — allows for morphing of defilers, as well as the Plague and Consume evolutions and an energy upgrade. Requires hive.
- Ultralisk cavern — allows for morphing of ultralisks, as well as (in Brood War), speed and armor upgrades for ultralisks. Requires a hive.
- Infested command center — can only be created by a queen. When a terran command center falls beneath half HP, a queen can infest it. Produces infested terrans.
The zerg excel at quick generation of armies, making them highly flexible. Each hatchery produces a maximum of 3 larvae and a new one every 20 seconds, making it easy to grow new units, and every hatchery can create any available zerg unit, unlike the specialized factories of the other races.
Their return cost is building expenses. Each hatchery/factory is extremely expensive (300 minerals and 120 seconds of build time, compared to for instance the 150-mineral 80-second terran barracks), and furthermore, each new structure must be grown from a drone (50 minerals, 20 seconds). Defensive structures are even worse: the drone must be hatched and then turned into a creep colony, and then the creep colony must be turned into a sunken or spore colony (for a total of 175 minerals and 80 seconds).
Because of slow building and Drone sacrifice, and moreover because of the need to build drones with the same limited early larva supply used to build attack units, zerg have the weakest starting economy. They make that up with their overlord, which can be immediately sent to scout, and the serendipitous discovery of an enemy base can lead to an early attack, something the zerg excel at. An early-game strike at the enemy's mineral line will usually even the odds, if it doesn't hand the zerg the advantage. Since hatcheries allow the building of 3 units at once, if the zerg survives to mid-game, they tend to catch up and even push ahead of the other economies. Their cheaper hatcheries relative to the other race's "town center" buildings also makes it easier for the zerg to take multiple expansions.
Zerg are particularly weak against well-defended choke-point unless you use a trump strategy. Due to the cheap cost of units, zerg fighting power cannot be concentrated onto one choke point efficiently. 24 zerglings can be stopped on a cliff, blocked by 3 zealots. It would be much wiser to attack from a different angle. In general, fighting in open space is best for zerg.
When zerg face off against each other, the game gets fairly predictable. Zerg vs zerg games usually involve only three types of attack units: zerglings, mutalisks, and scourge. This is primarily because hydralisks are not effective against combined zergling/mutalisk forces. Devourers are also sometimes used if the game lasts a long time. The queen's Ensnare spell, though rarely seen, can also be very useful in mutalisk air wars.
Another advanced tactic would be to "nydus" your enemy base using the nydus canal. Although, very hard to pull off and would give away your tactic (i.e. ground units, zerg race), if achieved, could hinder your opponent to a significant degree. This tactic requires early scouting to first know that the opponent is indeed zerg and would also require exposed creep in your opponents base that isn't defended so the nydus canal can spawn successfully. Of course, one may go to the extreme and construct more than one nydus canal, then try to make exits for each one.
Spawn broodling is very useful on ultralisks.
When the Swarm confronts terran foes, it usually faces one of two main tactics. The primary strategy employed by terrans, the dreaded tank push, is as effective against zerg as any race. A prepared cerebrate has several effective counters. Burrowed zerglings are capable of lying in ambush for approaching tanks and emerging practically on top of them, too close to hit. When protected from marine fire under the cover of a defiler's Dark Swarm, zerglings can quickly surround and destroy enemy tanks. Tanks can also be neutralized by a queen's Spawn Broodling. This is especially effective if the enemy deploys tanks in small groups: a tank that is suddenly turned into broodlings will attract the fire of other nearby tanks, distracting them, and damaging tanks or infantry close to the broodlings. This can also be used in the middle of a group of marines, or as a cheap way to damage bunkers prior to a base assault.
In the Brood War expansion, zerg face an additional threat: pure infantry armies of marines and medics, affectionately nicknamed M&M. These can deal significant damage to zerg forces while sustaining frustratingly few losses. Fortunately, the zerg now have lurkers, which are specifically designed to counter large groups of infantry. Lurkers benefit especially from good unit control: a cunning cerebrate will note the approach of infantry and continually order his lurkers to hold their fire until the enemy troops are right on top of them. This will greatly increase splash damage, and, when combined with surface troops, makes it difficult for the lurkers to be targeted, even after being detected.
In extremely long games, terrans sometimes opt for a large fleet of battlecruisers. These intimidate some zerg players, as they have no equivalent capital unit, and large groups of hydralisks will be quickly mown down. Queens and defilers are the answer here, as Ensnare and Plague will cripple the enemy and render them unable to escape. In Brood War, devourers and mutalisks are a highly effective combination. Scourge also show their quality in this situation, as they can take down expensive battlecruisers for much less cost. However, one must remember that, if unescorted and aided, no amount of scourge can score a hit on groups of six or more upgraded battlecruisers. Their upgraded weaponry will take scourge down in swarms. Valkyries can hit multiple targets but the zerg can use hydralisks to knock them out of the sky.
Terrans have few special abilities that are trouble for the zerg. Irradiate can be highly annoying, as a single use will destroy an overlord or lurker and can massacre a clump of mutalisks. It is largely ineffective against other units, however, due to the extremely long time it takes to work. Burrowing the affected unit is the best defense when it is used on a pack of zerglings or hydralisks. Irradiated mutalisks should be isolated from other units to minimize damage. Nuclear strikes should not be a problem as long as you keep overlords in every base; however, should a strike be targeted on an injured building, it can be difficult to distinguish between the tiny red dot and the building's blood.
Finally, although infested terrans are entertaining to use, their effectiveness should not be overestimated, as they are rarely able to reach their targets without dying. Dark Swarm can be used to prolong their lives, but it does not protect units from splash damage. In allied or team games with a terran partner, however, Defensive Matrix can drastically alter that.
Protoss players have to play a guessing game regarding the zerg's strategy until they have reliable data. Generally, zerg players pick a strategy at the start and later on change it to throw the protoss off balance. Mutalisks, due to their small size, are resistant to dragoon fire, and of course are completely safe from zealots. High templar, however, will decimate them if they pause in mid-flight. Hydralisks, if micromanaged properly, can defeat zealots without taking a single hit. Zerglings destroy dragoons due to their small size and speed.
The zerg will typically have massive numerical superiority against a much smaller army of far tougher units. This provides opportunities for dividing the army into smaller groups for attacks and harassment over a wider front. Dispersal, especially on the tactical level, may also provide some protection from the high templar's Psionic Storm, and the dark archon's Maelstrom.
Use comparatively inexpensive scourge to counter expensive protoss air units.