I am sure that my players are wondering about this question as they are working on characters.
As I was thinking about what to run I had a number or Criteria that I had to keep in mind. 1) Keep the genre easy for new players to understand so I gain player buy in of the campaign concepts. 2) To have something that could be run at short notice. 3) To be something both familiar and alien at the same time. 4) To have something that another GM could step into and run a decent game without long briefings being required.
Our group just ended a longish and fun Fantasy Hero game that left me both feeling good about how it ended, but also sad because it ended. This caused a bit of apathy toward running any fantasy game. I started to work on a SciFi campaign that was/is to be a fusion of StarWars, Serenity/Firefly, and Traveller. It became clear to me that it was going to take me too long to get that game together to run. Also SciFi games don’t appeal to all gamers. So I started to think about another game to run. My next idea was to run a slightly modified (translated to Hero) version of Ral Talsorian’s Castle Falkenstein. It was the first Steampunk that I had encountered and played. I like some of the concepts of the game, but gaming in 19th century Europe never interested me. I always wanted to run Castle Falkenstein in America with an old West feel. So I took that idea and ran with it.
I decided that players would probably have an easier time dealing with non-humans that they were confortable with, and not the Mythological Faerie. So I just decided that D&D style (Tolkein) Elves, Dwarves, Gnomes, and Halflings lived in Europe and had mostly integrated themselves into the Human Countries/Kingdoms. That some of the fantasy races had already colonized the Americas during their diaspora (going to the west as Tolkein’s elves did). So there would be Fantasy races that were fully integrated into human society, and ones already living in the Americas to contrast against. The races here would be living in harmony with the native American Humans. So the Native Elves, Orcs, etc would also be in conflict with the European settlers who have been around for the last 100years. Some of them would be fighting along side of the Native American tribes who are trying to be left alone.
Another difference is the fact that Magic works. Big spells like Fireballs and other D&D staples. I am thinking that those spells are only castable by a small minority of people. This small minority along with the power of firearms being the reason that casters didn’t dominate warfare. I am thinking that the rarity will be along the lines of everyone knows of an individual in town that can cast some sort of minor spell. People who can cast large spells are few and far between. There are also denominations of the Christian Faiths that see magics as a gift from god and can cast devine spells like healing and blessings. Though only the most pious and gifted can do so. The non-christian gods of the Native Americans and Non-Humans can also grand healing spells. etc.
So far I have decided that History has gone the pretty much the same. I am thinking about some little changes to history. Not enough to be really different, but big enough that it would need some sort of explanation. As I am still deciding on things like a Elvish American territory that is east of the Mississippi. A piece of land that is carved out of parts 4 or more states that are forested areas. I also have to decide what this heavily protected bit of forest would have done to the US Civil War and how it was fought.
So hopefully something will grab my players and we will be able to have a fun game.