Concerning the facility:
The Varuna Project was originally a resort that reluctantly accepted refugees in the early days of the crisis on the surface. Subsequently large areas were adapted or built onto the facility to make room. The largest of these areas is known as "The Hallows" where many descendants of the original refugees still live. The facility was largely under the control of its founder Tadashi Takahara and his company NANTEC. Tadashi, however, has become increasingly reclusive and the recent murder of several NANTEC board members has broken their assumed control of the facility.
Concerning the founder:
Takahara was a billionaire entrepreneur who got his start in smart weapons and AI. Famous in the world before, he had the ear of many prominent leaders and forever sought the next trans-human technology. Cybernetics, genetics, and AI, were all within his areas of interest and any company who found some large development was bought up by NANTEC, who presumably still studies all these areas today. Takahara is now a very very old man and has become increasingly reclusive to the point that few now have seen him in many years.
Concerning NANTEC: NANTEC is still a premiant power within the facility. When it comes to new developments and the solutions to technological or medial problems they are still the only ones within the colony who can help. Though there power has slipped somewhat lately, they still maintain the rules about selective reproduction and control on cybernetics. NANTEC also has strict rules about exposure to the virus. No samples of the virus are permitted anywhere in the facility for any reason. Any exposure or attempts to bring samples or infected organisms into the facility is met with extreme force by NANTEC.
Concerning the virus: The virus is known to be very successfully airborne but not waterborne. The recent necessary runs to the surface have so far proven to be safe with the proper respirator systems. The virus is known to induce mutations in its hosts. These are random, ugly, and usually fatal.
Concerning the surface: The surface has largely been reclaimed by nature. At this point most animals have been mutated to be very different than humanity remembers. However some versions of mutations have won out to creature horrible species that have adapted to the virus. These species are largely much more dangerous and unpredictable that the creatures from which they descend from. Plant life, which was largely unaffected by the virus, has overgrown every part of the surface and created new forests where once there were cities.
Concerning other colonies: Other colonies are out there and can be communicated with. Migration is rare, expensive, and dangerous. Most of these exist as either underground or underwater facilities which makes reaching them physically or even in communication unreliable. Trade is nearly non-existent.