What makes one species different from another? Oh, I should back up a bit; what makes one game species different from another game species? The answer, typically stat bonuses. Good example: elves tend to get a bonus to dexterity over humans or dwarves being hardier than humans. The gist is being in most gaming system, humans are the baseline by which other species are measured and for the majority of the time other species are measured better.
Where do humans shine in game systems? Background material where humanity is the majority of the population, governments, civilizations, and power. Sure other species are better than humans in just about every measure, but for whatever reason they are always the minority in a game and/or have a singular government and civilization. Why dwarves never bought out humanity or crushed them under their armies or elves realizing humanity would make great workers or pest eliminated them outright I will never know.
That is what I have been combating with my setting. In Stroud there are many species. If humanity is the majority of the population, why and where do the other species fit in and why. I am choosing to present deeper background information for each species over a set of bonuses that separate one species from another. Plus, if I am being honest, years of playing and running games I am sick and tired of the stat games people play to create an optimized character. I don’t blame them, I do it myself, but I am tired of it, thus for my game there are no stat bonuses.
Resuming the example of an elf being more dexterous than a human, why is this not expressed in other ways beyond bonus to shooting, being hit, and the other standard tropes? Imagine the things a species noticeably more dexterous than humanity could do and probably would do or a species healthier or stronger, it is a wonder that humanity is the majority species in any setting.
I have focused on areas where species differ culturally, such as cymeans who have sensitive skulls and family patterns of spots on their skull and down their backs, they do not wear hats, like having their heads touched, and clothing has open backs to display family spots. Illietheril are risk takers which is why many illietheril youth find their way into extreme sports and risky activities such as exploring the catacombs under the city. Korogin formerly a nomadic tribal species evolved into expanded families, a love for hover bikes, and a talent for fixing them.
My hope is players choose a species because there is something more than a non-existent bonus to an attribute that catches their eye and imagination. They take that and run with it creating new stories of their own.