Thing is, even if the alien is a biped the psychology of the race would have to have some degree of difference. And not in the woo woo alien space magik sense [referring to telepathy or "being one with nature innately" or having monolithic dullbore hive mind wankery], I mean in the way they think. For instance their intelligence may not do things or act the way humans do, even if their brains converge with the human brains in many ways. One example being that they might only do actions and not have internal thoughts, instead constantly needing to be communicating to others of their kind or inanimate objects if alone and despising silence, and constantly be around anything they believe they can communicate with. Or perhaps in the opposite direction, be naturally inclined to territoriality Instead of communalization despite being able to process information far quicker than humans can. 

Or perhaps the alien is highly eusocial and despite members having individual thought have castes that mindlessly obey the orders of higher ups in their presence due to natural pheromones with reproductive drives existing only for a minority of their kind. Such alien race may not have be a hive mind, and in fact could be oligarchical instead of having central control of a queen. 

Humans like you or me I see generally as a social race that work in groups that have leaders to them. In contrast, there could be social aliens that have communal groups lead by other groups instead. 

Could multiple players agree to follow a alien mindset? Of the alien psychologies I've mentioned, which one is best for RPing with that isn't too humanesque? I don't want the aliens to be like humans since when humans can have genetic modification and all sorts of odd societies making the aliens like humans wouldn't contrast well and if too human-like they minus well have been a lost colony.