This is one suggestion I'd really like to see fly. It makes sense to implement it but because of how the site is currently structured it may take more coding than Alex is willing to do to change it. Hopefully it's either not too hard to implement or Alex wants to do it.
Anyway - essentially the idea is to turn categories into tags.
There are storygames on CYS that could be considered both Horror and Modern Adventure, or are both Sci-Fi and Fan Fiction. You can't put your storygame into two different categories at once, which makes it difficult to classify, say, a time-travelling storygame where your character experiences both the past (Fantasy) and future (Sci-Fi).
What you can do is give your storygame multiple tags. Instead of categories, we could have a Fantasy tag, a Modern Adventure tag, a Fan Fiction tag and so on. This would solve the problem of only being able to sort a storygame into one category.
Worried about no longer having featured storygames? That's not the case. Instead, you could have certain tags that are featured on the Storygames page, similarly to how categories are displayed on the Storygames page now.
Anyway - I'd really like to see this FWW request become a reality. Especially now that we're in the process of upgrading the whole site.