We have a rule that says that is a question is more centered on a story than on a world, then there should be a Vote To Close for being off-topic.
For example: How to safely check if you are immortal?
This kind of question can possibly be saved by using the "In a world..." defense.
"In a world" is voice-over artist Don LaFontaine's gift/curse to movie trailers. While an utter cliché today, it became a cliché because it works. In a movie trailer, you — as the author of the trailer — have the audience's attention for a few seconds. In those few seconds, you have to explain the premise of story without making the audience become bored, or making it feel contrived. So how do you do that?
Don found that using "In a world..." allows you explain an entire setting in one sentence, while at the same time placing the protagonist(s) in that world. "In a world..." works as a glue between a setting (which is that which we are primarily concerned with at Worldbuilding SE) and a story (which is what the offending question was actually concerned with).
Point for discussion
A question such as the one exemplified above I feel could be saved by re-writing as such. The original phrasing goes from...
My character is told they are immortal. How should they test that?
In a world where people are told they are immortal... how would they go about testing that?
Should we add the "In a world.." defense to the Too Story-based: How To Fix-section and — if applicable to a Too Broad question — tell the user to fix the question as such?