I can't remember where I stashed it, but a few years back I tried making a RP where everyone had to be hive minded insects on a giant desert planet.  No humans, just lots and lots of alien bugs crawling around.

The essential idea being basically to have everyone to share a alien species instead of having individual players use their own species.  So instead of emphasizing cultural differences by species, players would have to be more creative by having to figure out cultures that are consistent with an alien species.  So, a egg laying species that is hive minded may have different sets of social norms even if they all generally share a common value for communization.  Hiveminds I figured would work since each hive's "culture" would also be said hive's "personality" and that interaction between millions of individual insects could be expressed as interaction between collective sets of consciousness.

The problems with an RP like this is are as follows:

1. it's a sci-fi RP with pre-industrial tech that isn't using noble savages or a Cowboys and aliens narrative.

2. There's usually only a couple people who like being the hivemind in a sci-fi RP.  Making everyone the same species of hivemind, even with a hivemind that does not have peaceful unity would likely come off as "too creatively limitting".  I disagree with that notion (as you can expand upon a individual species in-depth and find the complexity of any galactic space opera RP), but the mere perception is all that is needed to ensure a dead RP on arrival.

Other variations on the concept include using AIs on a interstellar/galactic scale with swarms of drones since that is what space NRPs tend to be anyways or using a humanoid species instead (but at that rate you minus well be making fantasy).