I wonder if there aren't any group rationality games that don't seriously undermined group moral and cohesion. The last time I played Mafia people ended up crying and my relationship with my brother and cousin went through traumatic upheaval. Diplomacy is not a better option.
This seems like an unusual experience to have. I have played Mafia with 3+ non-overlapping groups in person and 4+ non-overlapping groups online, and have yet to encounter any trouble; in fact, in two of the cases we were explicitly playing as a bonding exercise to improve group morale and cohesion, and it seems to have worked both times.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
If continuing the discussion becomes impractical, that means you win at open threads; a celebratory top-level post on the topic is traditional.