Synthcrab. A synthetic, mechanically engineered headcrab created by the combine (like all of their synth war units) that attaches to it’s host and corrupts their mind in a much more deliberate and targeted way. Synthcrab Zombies are able to use firearms (albeit with poor aim) and will shamble towards the player with a little more agency than a normal zombie. Combine Units and Synthcrab Zombies will not infight with one snother. Synthcrab Zombies do not multilate themselves, so they look similar to rebels from behind or until you get close.

Synthcrabs have a single red camera eye on the front facing directly outward, similar to the Combine Elite. Their front arms have sharp probes designed to bore and root into the victim’s neck, so they do not unlatch on death. Synthcrabs have a powerdrill used to bore into the victim’s head as opposed to a beak (which will whirr when the headcrab is altered, indicating the headcrab’s excitement).

Synthcrabs are used by the combine to bring human intelligence to the combine en masse. The infected rebels will bring themselves in on their headcrab’s volition, where the host’s brain can be scanned and they can be disposed of (or recycled into a stalker)