Rat-Hordes are small (1.5 meters tall), bipedal mutants with distinctly rat-like appearances, long rat tails, smooth (where not covered in fur) skin, and greatly elongated hind limbs. They inhabit exclusively the sewage collectors and lower technical levels of the Moscow Metro, preferring dark, damp, and hard-to-reach zones for humans and other larger mutants.

Rat-Hordes are a direct consequence of the same events that gave rise to the Skavens. During the Rat Invasion of 2014, when grey hordes of rats poured from the depths into the Ring Line, the “Biomorph” (https://lemmy.world/post/44620460) pseudovirus ensured bidirectional horizontal gene transfer. If humans infected by rats turned into Skavens, then the rats themselves, biting and devouring infected humans, acquired human genes.

Thus, two parallel evolutionary streams emerged simultaneously:

• Humans → increasingly rat-like (Skavens)
• Rats → increasingly human-like (Rat-Hordes)

As they only appear in the canceled game Metro 2033: Online in the canon, reliable information about them is extremely scarce. It is only known that the first reliable encounters with bipedal Rat-Hordes occurred in the sewers beneath the northern part of the Grey Line and in the Savyolovskaya area – precisely where the main wave of the grey horde was once stopped.

Physiology

The main difference between Rat-Hordes and Skavens is the speed of evolution. Rats reproduce dozens of times faster than humans. A female can give birth just two months after her own birth, and a new generation appears every 2–3 months. Over the same 20 years, during which Skavens saw only two generations, Rat-Hordes could have gone through 30–40 generations (although the birth rate noticeably slowed down after the appearance of pronounced anthropomorphic features).

Key physical characteristics:

• Head — entirely rat-like, with powerful incisors, long vibrissae (whiskers), and black eyes without whites.

• Body — almost smooth, hairless (fur is retained only on the head and in the groin area), which clearly indicates the manifestation of human genes.

• Limbs — long and powerful hind legs, allowing for confident bipedal movement. The forelimbs are not much shorter, but still long, with developed fingers and claws suitable for grasping and simple manipulations.

• Skin — smooth, grey-brown or pinkish in tone, often covered with slime or moisture from the sewers.

Behavior and Social Organization

Rat-Hordes do not possess reason in the human sense. They remain animals – albeit very cunning ones. They are capable of:

• setting organized ambushes,

• using sewage pipes and ventilation for surprise attacks,

• remembering the location of traps and stalker routes,

• coordinating actions within large hordes.

Their behavior is closest to highly organized predatory packs: they hunt collectively, defend territory, and sometimes even demonstrate a primitive “division of roles” (scouts, fighters, “nannies” for the young). However, they lack language, culture, tools, or a societal structure.