Mars - History: Mars is the twin planet of Terra, and one of many long-inhabited Human colony worlds located near the Cradle of Humanity. It is the homeworld and primary power centre of the Adeptus Mechanicus, the ancient and byzantine Tech-priests of the Machine God, and the heart of their galaxy-spanning monopoly on Human science and technology.Following the Unification Wars in which the Emperor of Mankind defeated the techno-barbarians of Terra and reunited Humanity's homeworld under a single government, He concluded the Treaty of Mars (known as the Treaty of Olympus Mons within the Mechanicus) with the Cult Mechanicus to unify both Terra and Mars under the umbrella of the newborn Imperium of Man in the late 30th Millennium.The ancient Mechanicum government of Mars recognised the Emperor as the Omnissiah, the Machine God incarnate, and swore to lend their technology, the mighty war machines of their Titan Legions and all of their production facilities to the purpose of His Great Crusade to reunite all the scattered worlds of Mankind beneath the rule of the Imperium.In return, the Emperor promised the Mechanicum that it could maintain its political autonomy on Mars and all of its other Forge Worlds across the galaxy and that it would remain immune from adherence to the atheistic doctrine of the Imperial Truth. This ensured that the adepts of the Mechanicum could still maintain their faith in the Machine God.Therefore, Mars is just as important to the Imperium's survival as Terra itself, a reality reflected in the emblem of the two-headed Imperial Aquila, one head for Terra, the other for the Red Planet.In ancient times, Mars had a fully terraformed atmosphere and ecosystems very similar to that of ancient Terra during the Age of Technology, but the constant warfare of the Age of Strife and the later rapid industrialisation of the surface after the Mechanicum secured total control over the world destroyed Mars' manufactured oxygen-nitrogen atmosphere and restored the Red Planet's surface to its primordial desert state, absent surface water and breathable oxygen. The only inhabitable regions of the planet now are the Adeptus Mechanicus' hive cities -- called "forge cities" or just "forges."More than any other Human-settled world, Mars possesses huge repositories of technical knowledge. Its immense libraries and databanks are highly eclectic and disorganised; one delving for secrets may find a crystal storage device containing vital genetor-level data tucked inside a scrollprint for militarised locomotives.The planet itself is a wilderness of polluted ochre desert broken by metropolises the size of tectonic plates. Here the rockcrete spires, marble arches and flying buttresses of a standard Imperial world are joined by corroded steel, iron ventilation chimneys and shining glass pipes.Extensive travel tubes pass above crackling tesla coils that power construction sites and ancient industrial wastes alike. Shining new buildings braced with riggings of steel contrast with shattered condensation traps and the ruins of millennia-old wars. The older districts are dotted with broken plasteel slabs and twisted girders, the occasional solitary tower pointing purposelessly toward the Martian sky.Mars is strictly stratified in its social order. The Red Planet is ruled over by the Adeptus Mechanicus' fabricator-general, and the Mechanicus possesses almost every known piece of Standard Template Construct (STC) technology or designs currently in Imperial hands. This is ostensibly so that the Mechanicus can construct better and more durable vehicles and technology for the Imperium, although it is fairly clear that the Mechanicus is simply hoarding them.The lowest social level consists of the Martian citizens, mainly unaugmented Human populations who labour en masse at simple tasks such as sorting isotope scrap, tending hydroponics, breaking ore, stoking forges and so on.Most citizens aspire to gain status within Mars' theocratic society by joining the Skitarii Legions. In the process, they will receive their first battle-grade bionics and perhaps a way of later entering the full priesthood of the Machine God.Lesser citizens may sport tattoos and piercings suggestive of such bionics, but dress in common work clothes -- filthy coveralls, rad-tabards or cabled environ-suits. Regardless of station, Martians have a tendency to be burly, saturnine and shaven-headed, usually with a temper to match their dour aspect.All sport electoos -- subcutaneous cyberware that ranges from code-patches through which personal data is monitored to thick veins of electric cabling. Through these electoo circuits can the glory of the Omnissiah be channelled. In times of great strife, the masters of Mars' populace can use these interfaces to turn even the most gormless hab-worker into a dauntless warrior of the Machine God.It is also rumoured that the most powerful of the C'tan, the Void Dragon, considered by some savants to be akin to the ancient entity known as the "Dragon of Mars," sleeps somewhere beneath the surface of the Red Planet, in the Noctis Labyrinth.The presence of this entity may be the reason why Necron starships briefly landed on the Red Planet in 998.M41 for unknown reasons. Should the Void Dragon awake, the very heart of the Imperium will tremble.