When I’m dealing with a vague story idea that needs a context, I tend to attack it from one of two directions. In one case, I look for contexts I’m likely to be using in which it would definitely work: “This brand of Mystical Library would probably work in my game, or might be worth saving for The Game After My Game if I can find a culture concept that could carry it off.” In other cases, when I can’t think of those, I start looking for cases in which it wouldn’t work instead: “This brand of Mystical Library wouldn’t work in the Almagest-verse at all, and should probably be kept well away from That Thing With the Kobolds, Eira’s story, or anything having to do with The Company.”
But if you’ve been completely stuck on situations in which something would work, and full to bursting with things that definitely wouldn’t work, another approach is probably in order. That brings me to the approach I found tonight. Take one of the cases that would most definitely not work, preferably a relatively vague, flexible one. One that you think would be pretty cool if it were feasible. Take a close look at it. Now ask yourself, “Why won’t it work? Under what circumstances might it work anyway?”
You’re most likely to get something that falls into one of three possible results. One, it really is impossible, or at the very least improbable, and it’s easy to justify and hard to find even a convoluted path around—and that’s perfectly fine. Two, it isn’t so impossible, and figuring out how it would be doable will let you flesh out more of the details and push you farther towards having a coherent plot. Or three, while that particular idea wouldn’t work out for X, Y and Z reasons, you latch onto something similar that would, giving you the spark you need to get past this particular block.
Deliberating the merits of the possible is a good tactic; eliminating the impossible likewise. But don’t forget trying to work around the impossible—it makes us think while keeping us close to the idea, and that’s a springboard to inspiration.