Gonome

"Can you imagine what the next stage of mutation looks like?" - Scientist to Adrian Shephard

The Gonome  is the next stage of evolution for a Zombie. The Gonome appears in Half-Life: Opposing Force.

Overview
A standard Zombie is created when a normal Headcrab attaches itself to a viable human host by latching onto the head, and using its 'beak' to open the skull and expose the victim's brain. The Headcrab causes mutations in the host, such as rapid growth of finger nails, increased physical strength and increased resistance to harm. Another aspect of the mutation is a cavity (sometimes referred to as a 'maw') in the torso spanning from the neck to the waist. Whether this injury is due to the parasite devouring the flesh, or by neglect is unknown.

If a zombie is not killed and the headcrab is still attached mutations continue and a gonome is created. They're stronger, faster, and gain a ranged attack ability which consists of their throwing chunks of a damaging (possibly acidic) mucous-like substance at you.

Gonomes never appear in any of the other games in the series. However, they later gave Valve the idea for Zombines, though zombines have a "kamikaze" attack instead of a ranged attack.

The name "gonome" originates from the filenames. It originates from the term "Genome Solider" but changes the "e" to an "o" to match the the offical names of a headcrab.

Behavior
Gonomes generally stay with groups of lesser zombies and Headcrabs. If they observe any threat, they will first use their ranged attack. Should the enemy get closer, they will resort to manually attacking with their claws. They can sprint if they spot a distant target. In many ways, the Gonome's behavior is similar to that of a Bullsquid.

Gonomes seem to prefer dark areas near other zombies, as this gives them both a physical(darkness, other zombies)and a psycological advantage over the player.