Cystia may sound like a complex place, but it's far from it. As you can see in the map below, it's divided into four locations: the Housing Complex, the Lake-side area, the Forest, and the Ruins.
-Map not drawn to scale or to impress anyone-
Housing Complex: To put it simply, this is where your character lives. Building assignments and the other character who is to be your roommate are below the area descriptions and will be assigned after your character leaves a comment in this post about who they'd like to room with or at least stating which building they'd like to stay in.
Lake-side Area: Just as it sounds -- it's an area with some trees scattered around and a very large, deep lake in the center. As of right now, there's absolutely nothing wrong with the lake water.
Forest: Most of the wild foods (berries, nuts, herbs, vegetables, fruits, ect) come from here, as well as animals (yes, you can have your character kill and eat them. There's nothing wrong with the animals ... yet). Besides that, there isn't much else to it as of now.
Ruins: Herein lies the ruins of labs built on Cystia. It looks very much like a destroyed city. Your characters can find just about anything there -- strange chemicals, some basic weaponry, even a few dead bodies -- I left it quite open to leave room for the imagination here.
Really Big Tree: Solely for role-playing purposes and it's a pretty good meeting place for two characters to agree on. Some events will happen in front of or near 'Really Big Tree', too.
One-Person Housing: For characters who prefer to stick to themselves. It's the same as the housing complex, except there's no roommates (unless requested and under the agreement of both muns).
[[Just as a side note -- there are 10 characters to a building, meaning 5 pairs of characters to a building, and an infinite amount of buildings (since there's so damn many)]]
-Matt & Mello