A conversation with the OP of this question led to the following response (modified for the general audience).
Systems vs. Circumstances
Worldbuilding is the process of describing systems. People may be involved in some of those systems (e.g., a bureaucracy), but it's not the people you're building, it's the system. Here at WB.SE, the moment you ask about the actions or behavior of people (not systems), you begin running the risk of being too story-based (and almost always will be).
The smaller the "world," the less likely you're asking about a system
In times past we have described "worlds" as being of any size, from a multiverse down to a small town — but not individuals or even small groups of people (generally). The smaller the number of people you're asking about, the more story-based your question is. Ask about a single individual and with very rare exception, you're storybuilding, not worldbuilding. This is because even a god, when acting individually, does not constitute a system. Rather, the actions of even so consequential a being are circumstantial.
The most popular form of a story-based question is "How would somebody X?" This is asking about the actions or options available to individuals or a group of people (storybuilding). The questions we accept at WB.SE are about rules that would be applied to your characters, not how your characters would react... to what?
And that's the problem. "To what?"
A question about individuals is on-topic when asking about how those individuals would react to the rules (systems) of your world.
A question is off-topic (too story-based) when asking about how individuals react to circumstances in your world.
Systems vs. circumstances.
The definition may seem counterintuitive, but serves a purpose
Stack Exchange is not a discussion forum. But the moment we start helping people past what is essentially writer's block, a discussion is what we're having. To accomodate Stack Exchange's fundamental business model, we had to draw a line.
But never forget that Chat is your friend!
Nevertheless, please do not pass up the opportunity to use Chat (especially the Factory Floor), as it's frequented by many of our most active participants, and chat is where discussions belong. There, you can ask pretty much anything you want.
How do I get my question reopened?
You need to change your question to ask about a system, not a circumstance. It's possible that your question cannot be changed in this way because you really are trying to overcome writer's block and the circumstance cannot be disposed of. But if you are simply worldbuilding, you may have cornered yourself in the test.
What I mean by "test" is that rules need testing, and characters are frequently the subjects of the test. Perhaps the rule you're developing is that your world's atomosphere has a high concentration of nitrous oxide.
An on-topic question would be, how do I get my atmosphere to contain 15% nitrous oxide?
Another would be, are humans susceptible to 15% nitrous oxide such that they'd go around giggling all the time?
A potentially off-topic question would be, how would humans behave in an atmosphere of 15% nitrous oxide? (too broad)
But to make the too story-based point: how would my army react to invading orcs if my atmosphere has 15% nitrous oxide? We're no longer talking about a system, or the reaction of a group to the system. We're now talking about the reaction of a group to a circumstance that happens to involve the system — and that depends too much on your story (who has what weapons, how serious is the situation, what is the lay of the land, what resources are available, etc., etc., etc.).
But, the military engagement, which probably comes from your story, is really a test for whether or not it makes sense for your world's atmosphere to have 15% nitrous oxide.
Change your question to focus on the system, not the circumstances of the test.
