NodeBB or maybe piefed to host announcements and provide a place for questions and feedback.
Consider creating an account for each household with a “correct horse battery staple” style password that’s easy to input on mobile, print out a little slip of paper with an explanation blurb and account name & password, and deposit in their mailbox.
Do not expect any users until you’ve hosted several game nights that had multiple attendees. From what you say you are the events committee, not the online life committee. I would thus recommend to stay focused on events until people bring up, unprompted, a desire for more casual day-to-day interactions. You want to be integrating into their existing habits, not trying to replace them. Let the “switching” happen on their own initiative lest they feel like they’re being co-opted for your own personal agenda.








Also, no federation on the NodeBB/piefed unless/until the users overwhelmingly ask for it.