here's idea of civ:
while most civs have to choose between steam and magic (have i got it right? steam or magic, but not both), this one can combine both without any harm for themselves. however, they get meaningful penalties, which balance their versatility.
description: some kind of ghosts/vampires/whatever (maybe sidar style?), who lack some essence like soul and have to capture souls of another creatures for the possibility to develop their own techs and to grow powerful units.
how it works: you kill someone, get his soul, transport it to your city, refine it, then [keep it in city to boost science]/[invest it into some unit as powerful promotion]/[accumulate some more to combine into "high-grade" soul
].
the power of civ is polymorph: enemy souls can be used for any purpose needed, allowing, for example, to grow something like walking nuke-thrower (top-steam flamethrower + top-magic firestorm, both enchanted into one guy by the use of many many captured souls).
weakness: souls can't be "built" (or their passive income into civ is too low to keep satisfactory rate of evolution), they are only gained in battle - more you have already, easier you get extra one; once you loose powerful unit carrying tons of souls or scientific city (also needs souls to increase science) - it feels like disaster.
i'm not sure if this one will fit for new orbis conception, or is it possible to code.
anyway, thanks a lot for civ4-Orbis and FfH, played it a lot, like it much. hope to play civ5 version soon)