Factions

Behaviour Interactive studio head Miguel Caron has announced there will be five factions at launch, four of which are playable. Each of these factions will have 5 subfactions(Chapters,Warbands,Klans and Craftwords,for the Space Marines,Chaos Space Marines,Orkz and Eldar,respectivelly),in which the 5th one will be chosen by the community in the future.

Space Marines
The Adeptus Astartes (commonly known as Space Marines, and colloquially as Angels of Death) are the most elite and feared fighting forces of the Imperium. The primary unit of organisation is the Chapter, a self-contained army fully equipped with its own transport, non-combatant support staff, etc. There are around a thousand Chapters, each comprising a thousand Space Marines. There are far too few Space Marines to form the Imperium's main military forces; instead they operate as highly mobile strike forces. They are entrusted with the most dangerous missions, such as lightning raids behind enemy lines, infiltration, and tunnel fighting. Recruits are chosen from the best warriors among humanity. Naturally, this makes Feral Worlds prized recruitment grounds, as such harsh and primal conditions produce the best warriors. However, Hive Worlds are considered the ideal source of potential recruits, the populace of the lower levels composed of some of the most murderous scum in the human Imperium. Whole gangs of hive scum are sometimes hunted down and captured for recruitment. Among the most valued traits in a recruit are aggression and psychotic-level killer instinct. Much more rarely, certain Civilised Worlds are also recruited from. The potential recruit is first subjected to testing, including tissue compatibility tests and psychological screening. Relatively few get past this initial selection process. Those that do pass are termed "neophytes", and the process continues with the surgery, indoctrination, conditioning, and training that will make them Marines. The surgical process takes a great deal of time. The recruit receives implants, along with chemical- and hypnotherapy, and training necessary for allowing the functioning and development of the implanted organs. The implants transform their bodies and minds and give them inhuman abilities - making them capable of spitting acidic venom, absorbing the memories of the dead by eating their flesh, darkening their skin to protect it from radiation, and operating for long periods without sleep by switching off parts of their brains at a time. After this implantation process and the associated training, the recruit becomes an "initiate". Intense indoctrination and conditioning strengthens the recruit's resolve and increases mental capabilities, honing them into dedicated and merciless warriors. After more general training, they join the Chapter as full "brothers".[

The Space Marine Chapters announced to be featured are the Blood Angels,the Dark Angels,The Space Wolves and the Ultramarines.

Chaos Space Marines
The Chaos Space Marines (also known as Traitor Marines, Chaos Marines or Traitor Legionnaires) are counted among the most favoured and powerful servants of the Powers of Chaos.Technically the Chaos Space Marine Legions are the only Space Marine Legions still in existence, the loyalist Legions having been reformed into self-contained Chapters after the Heresy. Though the Legion remains alive to the Chaos Marines as an identifying concept, in reality all of the Chaos Legions have over time been scattered into separate war bands following rival Chaos Champions. On occasion a highly favoured Champion of Chaos, such as Abaddon, is able to temporarily reunite these Traitor Legions against the Imperium. Over the millennia the energies that saturate the Eye of Terror have worked their transformative effects on both the living flesh and the inanimate weapons and armour of the Chaos Space Marines. As far as weapons and equipment, the Chaos Legions retain much of their Space Marine heritage. The bolter remains the main weapon even when it has been refigured into a fusion of biological and inorganic parts, or redesigned into strange and baroque forms by the whims of Chaos or the user himself. Although power armour is often unrecognisable as once being Astartes-issue, the suits continue to function the same, and include standard auto-sensory technology, communicators and respirators. Armour has been recoloured and redecorated to show allegiance to the Legion's Chaos patron. Chaos Space Marines retain,for the most part,all the capabilities of their loyalist brothers,while mutated and improved by the favors and mutations of their diety(s).

The Chaos Space Marine Chapters announced to be featured are the Black Legion,the Iron Warriors,the Night Lords and the Word Bearers.

Orks
Orks are a warlike, crude, and highly aggressive green-skinned Xenos race. Orks are the dominant subspecies of the Orkoids, which includes the smaller Gretchin and Snotlings. Although their society is entirely primitive and brutal, the Orkoid race is also the most successful species in the whole Galaxy, outnumbering possibly every other race. However, due to their aggressive and warlike nature, this massive race is split into hundreds of tiny empires, warring as much between themselves as against other races. In the purely theoretical event all the Orks were to unite, they would undoubtedly crush all opposition. The Orkoid ecosystem includes several species, Gretchin, Snotlings, Squigs and Orkoid Fungus, as well as the Orks themselves. Orks are unusual in that they can continue to grow throughout their lives and that this growth is directly tied to their social standing - the largest Orks always being the most dominant. Orkoid physiology is a symbiotic combination of animal and fungus, integrated such that each augments the operation of the other and both work in perfect harmony. This fungus makes individual Orks incredibly resilient, replacing several vital organs as well as adding padding around those which remain. The fungus also fulfills the Ork species' reproductive function, and makes them one of the most proliferative species in the galaxy. Adult Orks are constantly releasing spores which lie in the ground, often for years, waiting to develop into Orks or Gretchin. Thus, a world invaded by Orks will be troubled by them for hundreds of years to come, and even if their initial attack is defeated, it is all but impossible to eradicate them completely. Ork "teknologee" appears ramshackle and slapped-together, but is as potent as any weaponry used by the Imperium. Ork technology is characterised by a constant stream of poorly thought-out experimentation and constantly trying to outdo the competition to build the biggest gun, the largest Gargant, or the fastest Warbuggy. Therefore Ork technology is not uniform, lending Ork Warbands a cobbled together and random appearance. Ork Mekboyz are specialists in the field of producing powerful Force Fields that can protect against damage, and at battlefield improvisation of repairs. They can salvage almost any burnt-out wreck, and many Ork vehicles have been reported destroyed dozens of times, only to be cobbled back together, given a fresh lick of paint (if even that), and sent back into the fray. The tough, resilient nature of Orks means they accept crude bionic enhancements, transplants, and other medical shenanigans being performed on them with ease.