There is the World Building community some mutual cross posting might bee good. @oblivioncubed is a Table top gamer/maker and may be interested. Also another to add mutual support wise might be the Tabletop Roleplaying Community.
With the advent of being able to pin post in communities, you could use your community as the central gathering place then have easy pinned links to more specialized communities.
One thing to not be overlooked in reach-out efforts is the simple fact that Hive Block Chain does have a lot of people interested in games and are willing to try new ones and give feedback, a great Beta Tester group so to speak.
I hope the community takes off, I have followed and will pop in every now and then.