My position is: 'When in doubt check the official rules'. Invasions are events, so let's take a look at the official rules pertaining to the events.
The scope of the WB.SE is described here:
Worldbuilding Stack Exchange is a site for designers, writers, artists, gamers and enthusiasts to get help creating imaginary worlds.
World building includes geography, culture and creatures for the world, not to mention magic and planetary physics, in short, everything from the physics underlying your reality to the entire universe you want to build. Links in the description below will take you to good example questions or more background information on the topic linked.
When asking questions keep in mind that the goal of the site is to help you build your world, not to tell your story.
If a system, event or element of the world is causing you problems we are here to help. If on the other hand you aren’t sure what a character (be it an individual or organization) should do, that is out of scope for the site, though we often have such discussions in Worldbuilding Chat.
Rules and guidelines applicable specifically to questions about events are:
General guidelines for all questions:
- Must be specific and answerable: What problem are you trying to solve?
- Must include context: What are you trying to accomplish? Context gives people writing answers an idea of what your end state will look like and why you want to get there.
- Must include restrictions/requirements: What will make one answer better than another? If any answer is equally effective your question is not properly constrained. How can this be executed? What tech, timeline, magic or other criteria apply to the situation.
- Should include research: What ideas have you considered, or what information have you already looked at or failed to find?
and
Keep in mind the following when asking about actions or events in your world.
- Events: Questions need to include the setting/situation and the event or, the result you are trying to get to and the setting/situation.
The linked post suggests these models for questions about events:
Or in plain English:
- I have START and CHANGE, give me RESULT : "What happens if I do
this?" (Good)
- I have RESULT and CHANGE, give me START : "How was it before?" (Good)
- I have START and RESULT, give me CHANGE : "How would I cause this?"
(Good)
The other combinations are not mentioned: having only one of these and
asking for the other two is always too broad. It's typical of unclear
or incomplete questions.
Other possibilities
- I have either START or RESULT : "Is this plausible?"
Asking information about something specific can be on-topic as
reality-check but can sometimes lack basic research. A lot of
questions asking about a good concept but with no tomorrow falls into
this category
In their answer to this post, Green suggests adding a WHERE clause
Where Clause
I think all we need to add here is a WHERE (condition) clause that specifies constraints on the scope of the answer. "Within" is another
word that could be used in place of "where".
I have START and CHANGE, give me RESULT within CONSTRAINTS on START
and CHANGE: "What happens if I do this within this specific context?"
(Better)
I have RESULT and CHANGE, give me START within CONSTRAINTS on RESULT
and CHANGE: "How was it before?" (Better)
I have START and RESULT, give me CHANGE within CONSTRAINTS on START
and RESULT: "How would I cause this?" (Better)
Suggested WHERE clause seems to be reasonable considering that there are guidelines for questions to be specific and contain restrictions/requirements and also this explanation from 'What types of questions should I avoid asking?':
Your questions should be reasonably scoped. If you can imagine an entire book that answers your question, you’re asking too much.
Another important rule is:
You should only ask practical, answerable questions based on actual problems that you face. Chatty, open-ended questions diminish the usefulness of our site and push other questions off the front page.
Please also consider this:
Some subjective questions are allowed, but “subjective” does not mean “anything goes”. All subjective questions are expected to be constructive. What does that mean? Constructive subjective questions:
- inspire answers that explain "why" and "how"
- tend to have long, not short, answers
- have a constructive, fair, and impartial tone
- invite sharing experiences over opinions
- insist that opinion be backed up with facts and references
- are more than just mindless social fun
For more detail, read about our guidelines for great subjective questions and blog post about how real questions have answers.
Based on the official rules, questions about invasions (invasions are events) are on-topic and should not be closed as long as they comply with the following:
- do not ask what a character (be it an individual or organisation) should do;
- specific;
- include context;
- include any 2 of these 3 aspects of an event: Start, change, result;
- include a set of restrictions/requirements;
- are reasonably scoped (not too broad);
- are practical and based on problems that the questioner is facing;
- if the questions are subjective, they must meet the criteria of good and constructive subjective questions.
Please note that the official rules do not talk about the reuse value of the questions or the answers. There is no requirement for questions to deal only with problems that can be applied to other worlds, settings, characters, etc. The requirement is to ask questions that are based on the problems that the questioner is facing (does not say how obscure, uninteresting, or unique those problems are).
Please also see how the scope is limited: Every aspect of the world is on-topic as long as it is not about what a character should do.
I guess, the part that creates the most confusion is 'what a character (be it an individual or organization) should do'.
There is a difference between 'should' and 'can'. While the former deals with specific actions and decisions, the latter is about capabilities, opportunities, possibilities, and available choices. Actions are something that characters choose (or the author chooses for them). Possibilities, opportunities, and available choices, on the other hand, are determined by the world and its systems rather than characters1.
In other words, a question like 'Should country X attack city A?' (without any specifics, just this question) is off-topic. However, a question like 'Does country X have a capability to attack city A given these specifics?' should be on-topic (albeit, there is a risk that this kind of question is too broad or does not contain enough information to be answerable).
Notes:
1 It is possible to make an argument that capabilities, possibilities, opportunities, and available choices also depend on characters. It is true to some extent. However, characters influence all of those in a systemic way and characters, in this case, do not function as individuals but rather as representatives of a class with specific traits. All of these allow us to establish causal relationships and build predictable systems where characters are just some of many elements.