Working on Sub-levels of level 0 and entities
Level 0.1 is an enormous megastructure found embedded in Level 0. Although it's large enough to be considered a sub-level, Level 0.1 is believed to be contained entirely within the bounds of its parent level. One notable detail about the threshold between Level 0 and Level 0.1 is that when viewed from the sub-level, Level 0 appears to be a series of nearly identical floors stacked vertically on top of each other, but attempting to breach the ceiling or floor of Level 0 from elsewhere in the level does not lead to other parts of the same level.
Level 0.1 is made primarily out of metal and glass, and features several different rooms and chambers, which are built using a smooth, almost futuristic style of architecture, though the majority of the structure shows extreme signs of damage with exposed wires and broken electronics found in many parts of the sub-level.
Although the sub-level is far from being completely mapped, an enormous hollowed-out section in what is believed to be the centre makes it possible to get a good idea of the general shape and structure of the level as a whole. It is believed that the sub-level takes the shape of an extremely large, spherical shell that surrounds the aforementioned cavity. The shell itself is extremely thick, generally having the width of dozens of city blocks.
Within the shell is a large variety of brightly lit rooms, with bedrooms, kitchens, gyms, and even some hydroponic greenhouses in various states of disrepair. Many of the rooms in the level are connected with automatic sliding doors, some of which are perfectly functional, despite the decay around them. There are also many automatons of various designs roaming the sublevel. The few that are working perform automated tasks such as cleaning and cooking.
Wanderers can easily pass between Level 0 and Level 0.1 by simply walking from one section to another. Due to the vastness of Level 0, however, coming across Level 0.1 in its parent level's halls is extremely unlikely. That being said, it has been suggested that the B.N.T.G. may have access to an, as of yet secret, method of reliably encountering Level 0.1 due to the prevalence of material from the sub-section in their possession.
Aside from simply travelling back to its parent level, Level 0.1 can also be exited by random noclipping, usually leading to Level 1, similarly to Level 0.