I use Blood on the Clocktower to do this, it's a social deduction game (that's just not randomly accusing each other) so it gets everyone talking easily
It has been my experience that social deduction games are very attractive to folks who have problems socializing in day-to-day life. You can see them almost come alive when they are given the permission.
the one and only meetup i ever went to (that wasn't something vaguely work-related) was a Werewolf meetup (the game). It actually wasn't very social, but it was a bunch of people who were really into Werewolf. Which, really, was what it was meant to be (and it was fun, because i love to play Werewolf)