You're the author, you've got a quite broad authorial say here. In terms of tagging, your question could certainly be tagged flight and (less so) combat. You're completely within your rights to revert that edit. This sort of conflict allows people to intuitively clarify their internal folksonomy of tags, and is therefore useful.
With regards to this question, the first clue is that the tag wikis and excerpts for these two tags are awful. They don't tell us what should or should not be discussed in these tags.
For my personal use, (especially as I tend to be very... sparing) of tags, I use them as "questions about X" so, therefore, I would see flight and ars-magica as a "question about flight in ars magica". Asking about flight in a game system follows almost the same pattern, though it disquiets me because the emphasis-of-question is different.
Again, this is because the tags flight and combat are worthlessly defined and so all that is left to us are our intuitions. I suspect that, if these two tags were to be improved, any concerns about their use would be greatly diminished.
Our site help defines tags as:
A tag is a word or phrase that describes the topic of the question. Tags are a means of connecting experts with questions they will be able to answer by sorting questions into specific, well-defined categories.
Tags can also be used to help you identify questions that are interesting or relevant to you.
Thus, people interested in flight, should be notified about a flight game-req. And people interested in interested in questions about combat should be notified about a combat game-req. ... kinda. Rephrasing it that way suggests the strong inclusion of flight into the tags, but the exclusion of "combat" insofar as it's not a question about combat as a question about flight in a game which has combat. Following that same pattern, though, allows us to then exclude both under the rule that "it's a question about a game (tagged) which has flight and combat." I'd say that flight is sufficiently novel of a feature to warrant a tag, and that combat isn't, but this is a grey area that should respect your authorial intent.
On the other hand:
"– they do not communicate anything about the content of the question."
under the meta tags discussion suggests that insofar as the question isn't about flight or combat, so much as they are features of a larger system, that those tags should be excluded. I can see that argument, but I'd weigh the "people interested in flight should see this game-req" as a higher priority thing-which-can-be-evaluated.
At the end of the day, we should use the above heuristic to guide our tagging efforts and improve the hell out of our tag wikis such that they offer better guidance as to the topic.
