The Tyranids

Tyranids are a nomadic alien race comprising many genetically engineered forms created from harvested bio-mass. They are an "elemental force" that seeks to consume all in their path, draining all planets of any possible resource with horrific speed and power. Tyranids are typically a close-combat army and rely on overwhelming their enemies through superior numbers.

Tyranids form a superorganism: they travel the universe on their Hive Fleets, destroying all ecologies in their path. They are psychically linked via their Hive Mind, which gives them great abilities to strategize and coordinate. When one Tyranid sees something, within an instant the entire Tyranid race is aware of it.

The mentality behind the Tyranid race can be summed up by the phrase "quantity has a quality all its own". From the lowliest Ripper swarm, to the deadliest Hive Tyrant, the signature trademark of Tyranids is that they swarm over their foes, obliterating everything before them without regard for species or race, seeing all life as merely fresh meat; new gene code to be assimilated, processed, and cycled into the spawning cycle to generate deadlier species off-shoots.


Description
The Tyranids are actually an extragalactic race of evolving creatures. Traveling in vast hive fleets in the voids of space, they are likened to galactic locust swarms, too powerful to stop and too fast to deal with. They migrated from other galaxies in search of more resources of bio-mass to consume, as their hive fleets 'devour' entire planets at a daily basis. Tyranids are bugs but have the image of a six-legged reptile.

Their hive fleets consist of millions of living crafts, each serving as the home of untold numbers of tyranids. These monstrosities evolve from bubbling geno-organisms in the ships' reproductive chambers. All these creatures are born to serve the ship, and the ship in turn exists only to serve the hive fleet.


The Organism
All tyranids are held in a common psychic bond. This bond enables the forces of Tyranid to think, perceive and act as a great whole, allowing complete command over its constituent parts.

From the smallest feeder organisms to the huge tendril-like shoals of the hive fleets, every Tyranid is bound to the will of the Hive Mind. The lesser and smaller creatures are mindless and instinctive, while larger more complex creatures can make decisions appropriate to the situation.


Psychic Web
They function in perfect unison, coordinated by powerful psychic imperatives transmitted by a communal sentience. Their fleets, hordes and broods do not have a single commander, instead, a synaptic web of psychic influence controls them.

For this reason, should the influence of the larger Tyranid organism be removed, the lesser creatures will revert to animalistic behavior.

The creatures that channel the commands of the Hive Mind are mostly, if not all, potent psykers. They communicate with their brethren not by language, but a kind of instinctive telepathy.


Growing War Machines
The Tyranids do not build their starships and weapons from metal and plastic, instead, they use gene-splicing and bioengineering to grow them from the living organic material harvested from the planets they consumed.

Every weapon, gland and projectile used in their armies is a Tyranid organism in its own right, from the spores polluting the atmosphere, to the grotesque spires that burst from the tortured ground during an invasion.


Tyranid Battle Tactics
Tyranids often attempt to first take a planet through infiltration. Space Hulks and other derelict spacecraft are infested with Genestealers, which quickly familiarize themselves with the layout of their new home, then hibernate.

When the Hulk is eventually discovered, the Genestealers attack the exploration crew, sometimes killing some crew members, but always leaving at least one survivor who is implanted with a seed.

This infestation is never fatal, but instead subtly alters the victims DNA, giving them a strong urge to mate. The child that results from this union will be a Genestealer hybrid, which now has the complete loyalty of its parents. The Hybrids continue to breed and multiply among the population, eventually forming a Genestealer Cult. As the Cult grows in numbers, it begins to spread its influence throughout the planet, placing its members in positions of power within the government and the military. At the same time, it begins to emit a psychic signal through the warp that acts as a beacon for the Hive Fleet.

As the fleet nears the doomed world, the cult goes into action, instigating a worldwide rebellion with the goal of weakening the planet's defenses against the approaching Hive Fleet. The Hive Fleet will also seed the planet with Tyranid organisms, which will begin to alter the planet's surface and ecosystem to make it easier to consume.

If the Hive Fleet is victorious, the fleet will descend to the planet, inhaling the atmosphere, drinking the seas, and basically consuming its nutrients until nothing more than a lifeless ball of rock remains.

On the battlefield, Tyranid tactics are based around the notion of superior numbers (try to outnumber the enemy fifty to one). Tyranids overrun opposition in close combat, closing faster than most armies. They possess few ranged weapons, but their sheer numbers and close combat specialization makes up for the slaughter if they are commanded by a worthy commander


Stages of the Planetary Devour
Generally, contact with the Tyranids occurs when a Hive Fleet invades a system for the purpose of harvesting its bio-mass. A Hive Fleet contains an enormous number of Tyranids, and they are brought to bear against resistance in the most efficient manner possible. Below is a general outline of a typical Tyranid planetary assault (in particular, this data is collected from the Tyranid invasion of Dalki-Prime):

* Day 00: Mycetic spores are dropped, mostly containing Lictors and Genestealers. As soon as they hit the ground, reproduction of Tyranid creatures likely begins immediately.
* Day 09: By now, Tyranids will have expanded to around 200 km around the drop point, and will likely present a significant threat to PDF troopers and resident Imperial Guard.
* Day 13: Tyranids have expanded to 700 km from the drop point; some may begin infesting local water sources.
* Day 37: Tyranids completely control the area within 2000 km radius of the drop point and basolithic infestation begun to reach to 5000 km radius.
* Day 48: Tyranid population growth skyrockets, with population doubling approximately every 3 days.
* Day 50: Main Hive Fleet arrives, craft generally numbering around 1.5 billion. Psychic contact with planet is cut off by the shadow of the Hive Mind. Any attempts to escape are quickly stopped by the Hive Fleet. Any remaining surface life is eliminated by Gaunts.
* Day 51: Primary consumption of bio-mass begins (resistance has generally been eliminated by now). Brood ships land, releasing Ripper swarms, which consume all organic material (even the other tyranids) and deposit it at the reclamation pools. Capillary towers (and the Brood ships) send the material into orbit.
* Day 80: Ripper swarms board the Brood ships and return to the Hive Fleet. The hive ships descend into the upper atmosphere and begin collecting it. Reduction in atmospheric pressure causes oceans to boil away, which are also collected. Lack of oceans causes plate tectonic shifts, dramatically increasing volcanic activity. Upon completion, the Hive Fleet reenters the Warp, in search of fresh prey.
* Day 100: Imperial navy arrives in response to the distress call, only to find a lifeless, bodyless planet.