Maelstrom is a new setting I'm brainstorming, one that started as a series of suggestions for Mr. Skrittiblak's Elysium Nebula campaign. These suggestions were aimed at giving greater depth and originality to a setting that that on the surface is a space opera starring the cast of D&D. (My impressions is that about half the suggestions were of use to him; the background I had in mind only partly overlapped with the secrets of the background he'd already conceived.) Over the course of our discussions I realized that if you took this fledgling concept and stripped away most of the elements that were being taken from stock science fiction and fantasy, the background meant to justify the presence of those elements could instead lead me to something intriguingly original.
Of course, this also makes the resulting concept really hard to summarize. I have only myself to blame.
The best way I can put it is this: You know how Firefly was the wild west in space? Maelstrom's "____ in space" is the world of the 19th century as depicted in fiction. And not just modern works, but a range of fiction that extends past pulp magazines to include the famous authors of the time, such as Robert Louis Stevenson and Jules Verne. Picture a vast and diverse realm- you have hard-bitten settlers eking out a living on the frontier, ambitious scientists racing towards new discoveries (that could lead to triumph a la Tesla or tragedy a la Jekyll and Frankenstein), intrepid explorers who venture deep into unknown territory, and strange natives of unknown civilizations whose leaders wield mysterious powers. The "civilized world" has its intellectuals and industry as well as its fair share of armed conflicts and bogeymen in the shadows. Mysterious foreign empires are known through countless legends and a handful of firsthand accounts.
Take that all, and spread it out not between continents but between large numbers of moons surrounding four gas giants which all follow the same orbital path around their star. In this solar system the would-be vacuum of space is instead filled with Aethereal mists and populated by an ecosystem of strange and varied creatures. Space fills the roles of both the open frontier and the high seas, as towering starships sail past herdsmen on crystal-winged mounts.
I don't see Maelstrom as resembling the 19th century in any aesthetic way- the 'space cowboys', for example, wear goggles and breath masks while having no need for wide-brimmed hats. I'm just using the time period as a guideline for creating a believable world of mystery and adventure; a place where society is close enough to our own to be sympathetic and understandable, without having advanced enough for you to know whether the note on the map saying "here there be dragons" is true.