The rocks show no real signs of erosion from air or water; it's very dry and cool in the vents, and the air circulates slowly through the station. However, in one direction you do find areas where the stone is worn smooth from continued use. Both on the ground and at about hip-level - or slightly above - the sheen of the rock indicates that someone has been walking through here regularly, relying on touch as much as sound. And these marks are, while not easily traceable, at least remarkable. Once they're pointed out, they're obvious, and so slowly, you follow those marks. The shaft angles down and then takes a ninety degree turn, then another, and another. The air is blowing from behind you now, and it's slightly warmer in front.
Eventually, the shaft opens up onto a high, cavernous area, and you find yourself looking down at the reactor that powers the entire station. You're about a hundred feet up. No one is supposed to be up here, so there's no guardrails or vent covers blocking your view.
The shaft overlooks the cathedral-like ducts and pipes of the reactor. Occasional arcs of electricity illuminate condensation running down the large plexiglass window that is there solely for the purpose of blowing out in the event of a reactor overload. The station would need to be saved, after all. The people could be restocked.
There's no clear way down from here, so you keep moving.
The tunnel continues its downward cubic spiral, and eventually ends at an intersection. To the left, a grate much larger than the one you started at is screwed in securely at one corner, but the rest are loose, letting it swing to the side to open your way out. The station's elevator is nearby, but its buttons are unresponsive. Overhead, lights flicker and buzz.
If you turn the other way, there is an endless labyrinth of gloomy tunnels, each slightly smaller than where you started. They all at some point lead out to rooms lined with maintenance access panels.
The entire level is hot and humid, and nothing is maintained well.