While designing my not-Star-Trek game, I needed to design some species.
Designing sci fi species is always an interesting challenge because it is constrained by the nature of the setting. Trying to come up with something interesting and avoiding stereotypes is fun.
My game, being lighthearted, can design species lightheartedly. This is a big advantage.
Since it's Not Star Trek, the species are all humanoid and largely based on Star Trek tropes. It's important that we are all humanoid so I can reuse body assets instead of having species-unique assets. The "funny-shaped-head" is valuable because the high angle focuses on the character's heads.
Each species has a species trait that affects how it socializes as part of a crew, and within each species there are a variety of personalities for individuals which change the flavor of their socialization.
Right now, the species I'm thinking of are:
Newcomers to the interstellar arena, humans are mostly known for their obsession with secrets. They want to be the galaxy's information brokers, but in truth they are just big gossips. Humans generate a resource known as "gossip", which can be transformed into drama by hanging out with others in the canteen. (Drama can only be generated during plot events if humans are not around.)
Human personalities include shouty, beguiling, chatterbox, curious, etc.
Space elves are an older, more mature race with a more mature demeanor. While most races think of them as extremely dull, oppressive bureaucrats, humans like them because space elves gave the humans a crap-ton of technology. A space elf can turn loneliness into inspiration by hanging out in the library.
Space elf personalities include stodgy, cold, overanalytical, observant, etc.
Onions are a young species that joined into the Star Collective because they were convinced it would be interesting. They were too young to realize that space elves are the most boring species anywhere. Still, they keep a cheerful face: onions generate a resource called "cheer", which is automatically substituted into any social resource conversion when an onion does not have enough of the required resource.
Onion personalities include cheerful, heroic, passionate, etc.
Robomans are synthetic humans created by the space elves as a test run for creating the Star Collective with humans. They aren't very good at being human, but they are very strong and clever. Robomans have extremely high physical and mental stats, but can only generate one social resource at a time, instead of all of them at once. You can change which gets generated at any time.
Roboman personalities include wannabee human, simhuman, "Danger Will Robinson" robot, logical, etc.
Anyway, each of these has their own unique head decoration for use with the tiny pixel view, so they should be easy enough to tell apart even though they all have the same shared body sprites (different builds are available, but not species-specific builds).