The upside of creating tags that drill down into niches is that it increases the resolution of the tagging system. The ideal really is that someone should be able to filter roleplays/checks by obscure tags, and people should be able to pick the most accurate tags that describe their roleplay. Everyone wins.

The downside is that the matches for each tag become more and more sparse. You either lump your roleplay into a more generic tag to increase its hit-rate (visibility) in filtered searches, or your give your roleplay a more granular (thus more descriptive, more fitting) tag.

I think I have a solution for this: tag hierarchies.

A tag can belong to zero or more other tags. Filtering on a parent tag will include all of its tag children.

For example, Cyberpunk and Space tags belong to the Sci-Fi tag. If a roleplay is tagged with Cyberpunk and someone filters roleplays by Sci-Fi, then that roleplay will show up. And, of course, someone can filter just on Cyberpunk as they please.

The key will be for the UI to express this and to keep it simple (no more than a few layers of nesting, ideally just one). For example, when filtering roleplays, clicking the Sci-Fi tag will highlight Cyberpunk, Space, and other Sci-Fi children so you understand the results you're getting.

Interest checks are more likely to choose generic tags, and roleplays are more likely to choose niche tags.