Controller

From Black Mesa: Wiki

A render of the Controller as it appears in Black Mesa.

Overview

The Alien Controllers share many characteristics with the other Xen creatures, especially the Nihilanth, suggesting that they may be a younger or smaller version of the Nihilanth's species, or that the latter may be a unique mutant form of a Controller, which gained power over its brethren Alien Controllers. Like these other sentient creatures on Xen, the Alien Controllers have a third vestigial arm growing from the center of their thorax. In addition to this, the Alien Controllers have disproportionately large heads, which could peel open to reveal an apparently mechanical spike or cone, resembling the interior of the Nihilanth's skull. Unlike the Nihilanth, the Alien Controllers have longer legs and were able to levitate without the assistance of a mechanical seat. It is unknown whether this ability stems from their strange psychokinetic powers, or from their seemingly mechanical parts. The Alien Controllers may have simply died out after Nihilanth's death.

Behaviour

They attack by firing multiple spheres of electrical energy (resembling ball lightning) from their hands, in the same way as the Nihilanth. They can also fire an energy ball from their head that is larger, more powerful and has a slight homing ability.

Alien Controllers are usually encountered near places where Vortigaunts are made to work. They seem to have had an unspoken influence over the Vortigaunts, making them fight or toil at a whim. This might indicate that the Alien Controllers share a limited version of Nihilanth's psychic enslaving power or act as an intermediary conduit, although their exact role in the hierarchy is unknown.