In thinking about the different character classes for Swords of Cydonia (still wondering about that title) and mixing in various cultures so that a party of adventurers might include a Cowboy, a Shaolin Monk, an Apache Medicine Man, and a former Buffalo Soldier it left me wondering what to do about the real historical issue of Racism in the Wild West. In the late 1800s this group of characters would almost certainly not have banded together, and most would receive an icy welcome at best in many frontier towns.
I don't want to be completely anachronistic with 2010 politics dressed up in 1880s clothes, but at the same time I'd rather have a wider selection of character options than you'd realistically find in a historically accurate campaign setting. What reason would the PCs and many of the NPCs they encounter have for moving past those real-world prejudices?
I think the answer is two-fold and ties back into the game itself. I find this pleasing because it feels a bit less like something I'm arbitrarily decreeing as GM from my personal politics, and more as something that just "makes sense" based on how the game setting and mechanics work.
People in any sort of Fantasy setting, and Adventurers in particular, need to contend with encountering creatures and situations that might cause their real world counterparts to lose their nerve, or possibly even their grip on sanity. If the town Sheriff, or a Saloon Girl would be capable of dealing with a world that had real monsters and magic in it without heading back East (which would be more historically accurate) then they would probably have the courage to look past simple societal xenophobia as well. The Apache Warrior looks a bit less alien to the New England Banker when they've glimpsed a creature with writhing snake like tentacles somewhere out in the wilderness!
Even more than the average character, a Player Character possesses the greatest capacity for personal bravery in the game. Every other NPC or Monster encountered has a Morale rating, and most could be forced to retreat or surrender during the course of an encounter. Players don't need to make Morale checks for their PCs though, and even if they play their character as a coward they have the *potential* for great acts of bravery. This suggests that more than any of the other characters in the game world they would be the least affected by racism, and be able to move past it.
This isn't to say that some NPCs might not be mistrustful of strangers, or even outright hostile to some types of character. There might still be lynch mobs in some places, or other dark reminders of the historical Wild West. What there won't be is a group of player characters who don't get along, or a starting town that only a fraction of the party can enter.
Reflecting on this I think it puts the game setting closer to Shanghai Noon (2000) and Wild Wild West (1999) than Gunsmoke (1955) - but the more I think about it, that's exactly where I want the game to be in the first place! :)