Tribe-based ?

I'm getting into post-apocalypse stuff a lot recently, and one of the more interesting ones is where nature reclaims the planet and everyone goes back to the hunter-gatherer system. Because of a diminished population, it wouldn't be that far off for siblings, parents and offspring, or other such close relatives to start procreating.

Actually thinking about doing this one myself, but it'd be nice to have a partner to help out, ya know? :P