This war left the Emperor crippled and dying, and he has since been immobile on the Golden Throne, a comprehensive life-support apparatus that sustains the remaining living cells of his body as he uses his vast psychic powers to combat the gods of Chaos and help smooth interstellar travel. Unfortunately,9 of the Primarchs and their legions gave their devotion to the chaos gods, becoming the Chaos Space Marines and bringing war to Holy Terra during a conflict known as the Horus Heresy, after the Primarch who led the attack. The Emperor created the Space Marines, and their leaders the Primarchs, for use in 'The Great Crusade,' a two-century effort to re-unite the far-flung colonies of humanity following a 'dark age' known as the 'Age of Strife'.

While the bulk of humanity's military power is found in the Imperial Guard, the Space Marines (Adeptus Astartes)вЂ“giant, 7 foot tall, genetically enhanced super-soldiers with world-destroying firepower and unswerving, fanaticaly loyalty to the Emperor of MankindвЂ“are the most famous. From here Abaddon the Despoiler, Warmaster of the servants of Chaos, launches 'Black Crusades' to conquer the galaxy in service of the Chaos gods.

The Warp and real space connect in some locations, notably the 'Eye of Terror'. Psykers, humans capable of mentally interacting with the Warp and capable of using 'psyker abilities' make up the bulk of the Imperium's information infrastructure, handling interstellar navigation and communication, but are always at risk of being perverted by the Warp or being possessed by daemons. The Warp is a realm without conventional laws of nature that evolves in response to psychic activity in real space, and is inhabited by the four gods of Chaos- Khorne, Tzeentch, Nurgle and Slaanesh-embodiments of vice who attempt to corrupt members of all races to serve their ends. Д¬entral to the WH40K setting is the existence of a parallel dimension called 'the Warp' or 'the Immaterium,' which is utilized for interstellar travel. Other playable armies include the Witch Hunters, Daemonhunters, Sisters of Battle and the Imperial Guard, organizations within the Imperium the Kroot, first introduced as a member of the Tau Empire and the Daemons of Chaos. the Orks, whose brutal personality, tactics and technology make them the comic relief of the series.the Tyranids, an all-consuming, all-organic, bio-engineered, intergalactic swarm.the Dark Eldar, who must consume the souls of others to prevent themselves from dying.the Eldar, an ancient and arrogant race whose psykers can predict the future.the Necrons, tricked by star-devouring creatures called the C'tan, the Necrons became soulless, constructs, made of living-metal, and after millennium of slumber they have arisen, seeking to reforge their lost empires.the Tau, a young and technologically sophisticated civilization of aliens that work for the 'greater good' of their empire and its inhabitants.The Imperium is at war with various alien empires, which include: In the WH40K setting, mankind is largely united in the Imperium of Man, which has expanded throughout the Milky Way galaxy. '.the grim nightmare of the far future, where there is only war and the galaxy's alight and everyone's got a headache.' - Dan Abnett in Eisenhorn Set in the 41st millennium AD, most of the major storylines that provide the backdrop and history span over millennia.

The Warhammer 40,000 game takes place in a dystopic, science-fantasy universe.

Warhammer 40k chaos gods