In StarCraft, there are three damage types: concussive, normal, and explosive. The actual damage done depends on the type and the size of the target unit, as indicated in the following table:
Units which deal concussive damage are optimized to kill small units such as zerglings and zealots. Concussive damage is limited more than any other damage type and is comparatively a rare attack mode.
Units which deal explosive damage are optimized to kill large units and buildings. Explosive damage isn't particularly effective against small units (which suffer half of the damage). Despite the name, many explosive attacks do not deal splash damage; for instance, the siege tank's attack in tank mode is optimized for destroying armored units, but it only gains splash damage when it switches to siege mode. Exceptions to the 'splash units are explosive' rule are the protoss archon, corsair, and high templar's Psionic Storm.
It includes all rockets attacks (e.g. missile turrets, goliaths' anti-air, scouts anti-air, valkyries, wraiths' anti-air), and all types of powerful cannons, like those of siege tanks and dragoons. It also includes the hydralisk's needle spines, the sunken colony's subterranean tentacle, infested terran's suicide, and the devourer's acid spores.
Normal attacks are effective against all types of units.
It includes all melee attacks, like those of the zergling and ultralisk. It also includes laser weapons (battlecruiser and wraith), most bullets (marine) and special cases (SCV/probe/drone's attacks, protoss photon cannon, archon, scout's ground attack, carrier (interceptor's) attack, zerg spore colony, guardian, mutalisk, and scourge)
Unit size is only loosely correlated with the size of a unit's sprite and the amount of space a unit takes up in a transport. Unit size is more closely linked to armor quality.
Most air units are large; indeed, all terran air units are large, even units which would be expected to be relatively small and lightly-armored, such as wraiths (compared to battlecruisers). Most powerful anti-air attacks deal explosive damage, as a result. The biggest exception to the rule is probably the mutalisk, which is small, but is expected to face explosive attacks regularly. Zerg scourges, protoss interceptors, and observers are the other small sized air units. Zerg queens and protoss corsairs are medium sized.
- If a unit is shielded (protoss only), the shield takes full damage from any attack, regardless of the unit's size and damage type.
- All buildings are "large" units.
- Some attacks may also deal splash damage, which damages units around the target. Splash damage typically affects all units except the attacker's own units; the exceptions are siege tank, spider mines, and infested terrans which affect all units.
In StarCraft II, units deal a base amount of damage and may gain bonus damage against certain unit types, as opposed to in StarCraft, where damage may be reduced depending on what unit type is being damaged. Damage is added on a "per hit" basis, and bonuses are calculated before armor is subtracted.
Attack types are more varied than in StarCraft, and can gain bonuses towards light, armored, biological, and massive units. Most units are either light or armored, which roughly corresponds to non-large and large unit sizes of StarCraft, respectively. Buildings are treated as armored and have the "structure" property. Some units, such as the archon, are neither light nor armored.
General Strategy (Damage Types and Unit Sizes). Blizzard Entertainment. Accessed 2007-11-20.