To answer the question, communities are server specific. There are 2 separate gaming communities on lemmy.ml and beehaw.org that I know of, and probably more by now.
About needing better documentation, I could not agree more! It's very understandable considering that just 3 days ago this was a place with 1k users at peak and 2 devs plugging away at improving the framework. This is an open source project, so be the change you want to see (not directed specifically at you, that's for everyone). We can make this whatever we want, but people need to put in work. Been trying to answer as many questions as I can reasonably answer for a few hours now :)