Space Marine II - Prelude: The game is set in the Warhammer 40,000 universe's 41st Millennium, during the Era Indomitus, the Age of the Dark Imperium after the birth of the Great Rift has cut the galaxy in two. After the resurrection of Roboute Guilliman, the primarch of the Ultramarines, as lord commander of the Imperium and Imperial Regent, the Imperium of Man has launched a galaxy-wide and a solar-decade-long campaign known as the Indomitus Crusade with the goal of reclaiming lost worlds from its myriad Chaos and xenos enemies and bringing it back from the brink of collapse in the wake of the Great Rift's opening.However, just when it seems that the Imperium has finally gained the upper hand, the savage alien species known as the Tyranids of Hive Fleet Leviathan emerges from its defeat in the Battle of Baal to launch a surprise assault from the intergalactic void upon the western Segmentum Pacificus region of the galaxy. This assault of the Great Devourer is comprised of a swarm containing greater numbers than ever seen before, and strikes the Imperium recisely where its defences are weakest in the wake of the Indomitus Crusade's first phase to secure the Imperium Sanctus. This great invasion marks the start of what will be remembered as the Fourth Tyrannic War.The game's main enemies are the Tyranids (believed to be a splinter fleet of Hive Fleet Leviathan) and the forces of Chaos. The Tyranids are an extragalactic insectoid race whose sole purpose is to consume all forms of biomatter. The forces of Chaos return from the first game, followers of the daemonic Gods of Chaos. Confirmed to feature in the game are the Thousand Sons, one of the nine Traitor Legions of Heretic Astartes who are devoted to Tzeentch, the Chaos God of change, ambition and sorcery.Following the events of Warhammer 40,000: Space Marine over a standard century before, Demetrian Titus, formerly the captain of the 2nd Company of the Ultramarines Chapter, was imprisoned by Inquisitor Thrax on charges of heresy due to his unexplained resistance to the psychic powers of Chaos during the Liberation of Graia campaign.Although he was eventually deemed free of Chaos taint, Inquisitor Thrax continued to imprison Titus for over a standard century and torture him, seeking answers the Space Marine could not provide. Thrax was later killed by the Grey Knights after being possessed during another mission by a Daemon.After Thrax's demise, other members of the Inquisition freed Titus and the other surviving prisoners of Thrax and allowed him to return to his Chapter if he so chose. Having received no word from his brethren since his incarceration, he came to believe he had somehow brought shame upon his name and that of his beloved Ultramarines and determined that he was not worthy to bear the Chapter's name. He would eventually enter the service of the Deathwatch, the Order Militant of the Ordo Xenos composed of Space Marines from multiple Chapters dedicated to hunting and exterminating all alien threats to the Imperium.  watch fortress Watcher Keep as a Deathwatch Black Shield, his former identity unknown to those he fought alongside.Overcome with shock and grief at his discommendation, Titus had all of his former Chapter's heraldry purged from his Mark VII Aquila Power Armour's battle-plate and assumed a self-imposed exile as an outcast Black Shield. Titus served with the Deathwatch for several solar decades.A tendril of the Tyranids' Hive Fleet Leviathan invaded the Imperial Recidious System in the Segmentum Pacificus as part of the Fourth Tyrannic War. Archmagos Nozick Beta-12 of the Adeptus Mechanicus had called for aid to defend the Jungle World of Kadaku in the system and to safeguard the classified "Project Aurora" being developed there.Titus, as the Deathwatch Black Shield named "Nullus," deployed as part of the Deathwatch's Kill-team Kasaeran, alongside Brother Ulfar of the Space Wolves, Brother Kelstros of the Blood Angels, Brother Beren of the Black Templars, and Brother Darius of the Dark Angels, transiting to the Recidious System via Corvus Blackstar. During their mission to the Recidious System, Nullus and his squad were tasked with reinforcing the Astra Militarum forces of the 8th Cadian based there on the Jungle World of Kadaku, who were already weakened by the toll taken by the Indomitus Crusade muster across the Imperium Sanctus. The kill-team's mission involved firing a virus bomb into the stratosphere using a local orbital launcher at the main swarm of the Tyranids in the hopes of killing enough of the bioforms before they adapted to the pathogen to give the Astra Militarum a chance at eradicating the rest of the swarm.The kill-team's gunship was brought down by swarming flocks of winged Tyranid bioforms, forcing the warriors to engage with the insectoid aliens on the planet's surface as they struggled to get the virus bomb to the launcher. During this mission, Titus was gravely wounded by a monstrous Tyranid Carnifex after he had fought off swarm after swarm of lesser bioforms. As life bled from his torn body, his fellow Deathwatch battle-brothers having all been slain before him, he prepared to commend his soul to the Emperor. It was then that Titus was reunited with the warriors of Ultramar, as an Ultramarines strike force arrived to relieve the Deathwatch at Kadaku.Varro Tigurius, Chief Librarian of the Ultramarines, detected the soul-sign of the warrior once known as Demetrian Titus in the local Immaterium as their strike craft traversed the Warp. Even as the Tyranids' Shadow in the Warp began to cloud Tigurious' witch-sight like cataracts, the Chief Librarian recognised he who had once been the captain of the Ultramarines 2nd Company.As fate would have it, Tigurius travelled aboard the Righteous Fury, the same vessel that had borne Titus and Trajan before him to battle many times, and it was this mighty voidcraft of the Chapter that broke from the Warp at the edge of the Recidious System. There, the strike cruiser prepared its Thunderhawk gunships to deploy to the planet where the broken form of the Black Shield known to his comrades as Nullus lay dying.The Ultramarines 1st Company arrived on the planet to reinforce the Deathwatch forces, bringing none other than First Captain Severus Agemman and Chief Librarian Tigurius. The Ultramarines fought valiantly, their weapon blasts wreaking devastation upon the Tyranid bioforms with the carefully born discipline of experienced Tyranid hunters, holding back the tide. They arrived too late to save Kadaku from falling to the Great Devourer but the Deathwatch warriors of Watcher Keep were able to recover their dead and wounded and fall back into the Ultramarines' gunships. All except the ravaged Black Shield Nullus, who Tigurius ordered returned to the Apothecarion bays aboard the battle barge Resilient.Titus' wounds were grave, and it was decreed that he would undergo the "Calgarian Rites," the Ultramarines' name for the Rubicon Primaris, in order to have even a chance of surviving. Titus withstood the procedures necessary to become a Primaris Space Marine as stoically as he had endured any of Inquisitor Thrax's interrogations and was remade stronger than he had ever been. When he awoke, he was surprised to find himself honoured with the rank of lieutenant under the command of Captain Sevastus Acheran of the 2nd Company -- a warrior who had only recently left the Scout Marine reserve when Titus was taken from the Ultramarines almost a standard century before. Once more Titus resolved to do as was bid of him by his Chapter, and serve under a warrior who held the titles he had once held.There were those amongst the Ultramarines who were apprehensive about Titus' return to the Chapter. Chief Librarian Tigurius, however, had performed his own examination of the former captain and found him to harbour no taint, before psychically communing with Chapter Master Marneus Calgar who authorised Titus' immediate reinstatement. Their word was as adamantine, and Titus was officially welcomed back into the warrior brotherhood of his gene-sire. Lieutenant Demetrian Titus, once and once more of the Ultramarines 2nd Company, would bring the wrath of his Chapter to the foes of the Imperium anew.