Would it be possible to add a sub-item called “Reviews” to “Adventure Games” in order to collect them?

For people to leave their own reviews of games, you mean? Perhaps at some point, but we'll probably keep things as is for now before we think about expanding. In my experience there isn't a lot of engagement on review threads, which rather defeats the purpose.

If anything, it might be worth exploring user reviews on the main site rather than the forums.