So here are a few setting ideas I got while riding the train. I've only tried one of them so far (Pantheon) and I'd love for people here to tell me whether they think those have potential or not and where they see pitfalls.
----- Goblon -----
When the British carved the Underground, they discovered a subterranean goblin city underneath London. Because they had vastly misestimated the topography of the ground beneath, a big chunk of London collapsed, killing millions of humans and goblins and laying waste to both cities. That was a few years ago. You are goblins and nothing if not adaptable, so, for bad or for worse, you've adapted to your brand new neighbours, the humans. Will you trade with them? Will you try to get them to accept you as equals? Will you exact revenge in the names of all the sisters and brothers they exterminated? And will you help them deal with the untold horrors of the underground that you have been dealing with forever and they can barely fathom, much less prepare against?
----- No sleep for the stranded -----
According to the Computer, you've boarded the EFS 124C two centuries ago. You should have arrived at your destination just about now, but something went wrong. All crew and passengers have now been woken up to find themselves stranded in a part of the universe that doesn't match the maps stored in the database. You have to wait a few days at least before going back to cryo sleep, or you'll suffer dire consequences and if you do go back to sleep, you first have to set a new course for the ship. What will you do? Will you try to find out what went wrong to maybe fix it? Will you explore the surrounding space on the lookout for recognizable landmarks that would tell you where in the goddamn universe you are? Will you look for a planet to land on? Will you try to contact your own kind or other sentient species? Will you pray that whatever gods you believe in might show mercy on you? And how will you deal with each other in such a crowded space, knowing each breath they take is one less breath of air you might eventually need?
----- Pantheon -----
You are gods. Immortal, impossibly powerful, vastly different from one to the next. For untold millenia, you've been content to let sterile conflict between you dictate your every move. But now, there is a new actor in the fold: humans. They were given fire and intelligence by someone of your kind (possibly one of you). They talk and think and dream and, most importantly, worship. Now, you've got much more interesting battles to wage: how much power should they be allowed to wield? How much contact should your kind have with theirs? Who among you will control their minds? Who will command their hearts? Who among you will get to shape humankind in their image?