Layers
The universe is divided into several layers. Some are, inevitably, more dangerous than others. All of us began in the Nexus area. Where we went from there was up to us.
Earthforce
Most of us probably stayed in the more "welcoming" central layer patrolled and maintained by Earthforce, referred to as Earthforce Space.
Wild Space
The further reaches of space are known as Wild Space for good reason. No one faction lays claim to this area, and not all are very welcoming of newcomers.
Perilous Space
Even further out, one stumbles into Perilous Space, where the more dangerous beings in the universe reside. It's said that far enough out in Perilous Space, one enters what's referred to as Perilous Perilous Space, where only the strongest have even the slightest chance of survival.
Minor Layers
In addition, there are several "pocket universes" of sorts that can be accessed from the normal universe, such as Arctia, Vulcan, or The Infernal Tempest. These are theorized to be some sort of sub-layers, each existing in a pocket of dead space between layers. However, that's just theory.
Shortcuts
There are also "Inter-layers." Juxtaposition, Concourse, and Subspace function as the shortcuts of the universe.
Juxtaposition gateways connect to a sort of sub-layer from which other, nearby Juxtaposition gateways in the same layer can be accessed.
Concourse sub-layers connect opposite ends of each layer of the universe (except, perhaps, for Perilous Space), with a gateway on either side.
Subspace gateways are capable, meanwhile, of carrying you between layers of the galaxy with ease.
However, there are dangers to these shortcuts. Their wormholes can only be entered by those with the fourth and highest level of skill in Warp Navigation. And once you enter, nigh-invincible Amoetroidizodals await you, one in Juxtaposition, two in Concourse, and three in Subspace.
Subspace
As a last note, the Subspace inter-layer should not be confused with Subspace proper. The Subspace layer is the most recently discovered actual layer, and is home to the extremely powerful and dangerous Aveksaka, an ancient race who pilot organic starships. Those entering the Subspace layer proper should be well-prepared, or they may not leave alive. (Note: accurate depictions of the flower-like Subspace layer are unavailable as of yet.)
