1. External Characteristics
Appearance: They resemble small crabs or chunks of chicken with four legs.
Size: Large enough to cover a human head.
Movement: They crawl slowly normally, but when attacking, they use the strength of their hind legs to leap high towards their target.
2. Attack and Parasitic Method
Host Control: They attach to a human's head, pierce the skull with their beak, and take control of the brain.
Zombification: The infected human loses their self and becomes a 'zombie' controlled by the Headcrab. The host's body undergoes grotesque transformations, such as elongated fingers. After attacking a person, they eat the corpse with their ripped-open belly.
3. Main Types
Standard Headcrab: The most basic form.
Fast Headcrab: Creates zombies that are very fast and agile.
Poison Headcrab: Black in color, possessing a deadly poison that rapidly depletes health when bitten.
4. Objective
They try to bite You and turn them into a host, and will parasitize anyone or any companion nearby without exception. No exceptions, as long as they are alive. Never.
Sometimes Fast and Poison Headcrabs may appear nearby.