How replayable is it?
neutronicturtle
Mysterium - something easy to learn and can be played by up to 7 people. One of the players is trying to tell others (psychics) who their killer is using very nice looking but rather ambiguous cards.
Maximum apocalypse - up to 6 characters doing different missions in different types of the apocalypse (zombies, nuclear war, aliens, robots). Map is randomly generated so even though there is limited number of scenarios they are replayable.
Sherlock Holmes consulting detective (multiple boxes) or Bureau of investigation - investigation in Arkham & elsewhere. These are text based puzzles (e.g. solve a murder case).
Spirit island - it's basically anti Settlers of Catan :) Still learning to play it but so far it seems like an amazing game with many scenarios...
I guess the communities have to be of certain size to function and to feel welcoming to post into. For the first point you definitely need enough active users to make it feel alive but the second point is probably very person dependent. To me commenting in the big subreddits felt to much like showting in a very crowded space (so I didn't comment much) while currently on Lemmy they feel more comfortably sized and somehow more real.
Perhaps for the same reason I never really "got" twitter. I understand it's usefulness for journalists or celebrities but for me it was too close to screaming into the void to be useful/comfortable.
As for Reddit, many people will probably stick to it simply through the force of habit.