I voted Mostly human, but then again, that's slightly skewed for us cause it is a human nobility campaign. We were sat down when creating characters and told we were all part of the same human noble family. Now, if we played anything but human, we had to have a damn good reason why we'd be accepted into the family. Also, he let us know beforehand that we'd be less well received as any other race but human by the other nobles. We've currently got 7 humans and 1 half-elf.
1) We're in a human controlled principality in a mostly human controlled world. Most of the people tend to be human. We do, however, have a large community of kobolds living on our lands as creatures "loyal" to our family. Our servants are all Elven, since that's what was readily available when we could afford to employ them. There is also a large community of bugbears nearby that raid our lands.
2) We have to deal with the less enlightened nobles occasionally. Currently, the story arc of this next year will be centered around a group of noble families wanting to round up all the elves (& half-elves) in the area and get rid of them (deporting them, most likely), due to their believed connection to an Anarchist group attemting to overthrow the nobility.
3)There is variation in the humans in culture and views throughout the world.
4) the demi-human communities aren't necessarily enemeis, but they are mostly obstacles.
5)War itself is a cause for many things in the campaign, but it is happeningin the background in a land several weeks away by boat. The war is the cause of the influx of elven refuges into the area, after all.
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As for our other game, well... We're all monsters. We've got 1 Fire Elemental, one Holiphant, one Hobgoblin, one Half-Ogre/Half-Dwarf, and one Lillend. It's a world of humans and we run into some open-minded people and some close-minded people. The close-minded are fun to mess with.