I don't have an exact year perhaps 832.M42 and it has not gone well. The forces of Order have been forced into cooperation with each other. Terran both Imperial and not, the Eldar and the Tau have consolidated around a few hundred star systems. After nearly 600 years of building the Ark "ship" is nearly done. The proto-world used as the core has supported the sprouting dome at the top and everything else below it. Untold numbers of all three races have already been settled the technology used to house them coming from the three main races. Space Marines are still produced they serve as their own Caste and Shrine. The MK XI "Alliance" armor blends the technology of the three races to make the armor more efficient and better. Armed with a variety of weapons to complete their missions. Beyond the Wall, the outer systems were the fleets are massed is a terrible place and these squads of marines are sent out to complete objections. Secure needed equipment, specific groups rescued and particularly dangerous enemy leaders need to be assassinated. Beyond the Wall between the forces of Chaos, Tyranids and Orks the galaxy is being completely consumed and destroyed. The 42nd millennium proved disastrous for the forces of Order and this alliance is the last chance any of them have if they want to avoid extinction. In terms of mechanics the game would use DeathWatch has the core rules but capable of using Imperial, Tau and Eldar weapons as well. Willing to work out specific armor bonuses for each player as they would have better customization of the Mk XI armor.