I haven’t played West Marches much. This one is going to be pretty wild, a science-fantasy campaign set in an incredibly ancient and enormous semi-ruined city (built upon the ruins of still older cities) on a bay. I’ve drawn on a huge number of science-fantasy and science fiction works for the background.

There’s lots of semi-working tech of all sorts from many of the civilizations that have been there, much of which is regarded by most people as magic. There are gene-tinkerers, scientists, amateur inventors, explorers, farmers, merchants, guards, secret societies, robots of all sorts, androids and other kinds of genetic constructs, aliens of all sorts (all long since stranded here or the descendants of the stranded, since the world is mostly cut off from other worlds), “ghosts” (hologram computer programs, most of them damaged and/or insane) and much more. There are also energy beings and “gods” of various sorts, although the more knowledgeable claim that these “gods” are either very powerful energy beings or ancient and unusually powerful AI.

The city is a place of many levels and layers, with ancient half ruined skyscrapers soaring imaginably high, providing perches for the city’s many flying denizens (animal, vegetable, mineral, engineered, and sapient). Several different types of underground railway and other forms of transportation lie beneath many parts of the city, although most no longer work or are partially blocked. Beneath that, layer after layer of archaeological ruins and mysterious machinery extend downward - some say to the core of the planet.