You know how many goths and cheerleaders you probably just insulted?
Yeah, all the cheerleaders who come to this site are going to be heartbroken.
***
Onto the topic at hand, I noticed this with a lot of books about Canada, which are almost always written by American audiences. RIFTS CANADA, for example, is all about arctic exploration. And a lot of modern games suggest that the second you cross the border, even in august, you better don a parka.
(This, by the way, amuses me in other venues, too. Like the people in Seattle I was talkign to in a Poker chatroom who assumed, in september, that I was covered in snow in Victoria... which is, um, within viewing distance of a part of Seattle. I said to them "hey, how is the rain down there? Because, you know, I'm under the same cloud as you.")
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There are going to be cultural biases in any game, and I think a lot of them we won't notice, as we belong to (more or less) the same culture. The freedom to choose religion is a big one in the fantasy games - it makes sense from a play standpoint, but we come from a culture where that makes obvious sense. Would it happen if the game were originally released in a fundamentalist state? Or medieval Europe? Probably not. That game would just assume PCs belonged to the "right" religion, and perhaps create an evil religion the PCs oppose.
Wealth and Magic Items are another example. Not every culture sees wealth in the same way as the west. I can think of many cultures where the acquisition of material wealth would not be seen as a good thing to emphasize (i.e., yeah, you want it, but you don't want people to know that you want it, so playing a game that is centred around it would be a bad thing).
Hell, the way these games are marketed speak to very Western conceit - RPGs are pure capitalism, and always have been.
But if we're gonna go with simple "American Centric" as opposed to "western centric", I honestly don't know. The imperial system is a good starting point. I think the idea of melting pot cities (where elves, dwarves, humans, and halflings happily congregate) would be a good starting place, since Americans often think of their nation as a global melting pot (not entirely true these days, or at least, no more so than most western nations). I used to think the town of Solace from Dragonlance was a miniature United States, in a way, for that reason. Also, the idea of "hive mind" meaning "bad guys" is a classic americanism that was probably stolen from the sci-fi of the time, since "hive mind" would be an analog to eastern communism (which americans, until a little over twenty years ago now, supposedly opposed).