I decided to see if I could make a jump-in roleplay on a whim, and about an hour later, this was the result. The actual thread explains everything that there is to be explained, which, as it happens, is precious little.

The characters are currently on the top floor of a city-sized industrial complex, its purpose unknown to at least one of them. Though populated with thousands of engineers, many are now hiding in the mist produced by damaged steam engines. The presence of unusual, if not otherworldly entities does little to soothe their fears. Brass pipes riddle the walls, and the windows show a vista of chimney smoke and lantern lights.

Link.