What do you call "narrative concerns"? The story as a whole, or maybe the "adventure"?
An example narrative concern would be not killing a prisoner b/c the story needs said NPC alive.
Some things that I have done to create realism in past games is
- have actions have global consequences. If you end all your fights by killing the opponents, word gets around. So does general professional behavior or lack thereof. Reactions are also influenced by the company you keep, or simply who you are seen with. The world responds to player actions.
- combat is painful and potentially deadly. There are no Standard characters. If you don't know what your odds are, characters approach combat a lot more conservatively, and sometimes even look for peaceful solutions
- The mission doesn't end at the end of the mission. Like the first point: evidence brings on the police, victims may seek revenge, etc.
As you see, I define "realistic" more in the response of the characters to the world and vice versa, rather than game mechanics, and I think you can run most games in a realistic Simulationist fashion.
Ah, in that case, you and I define realism the same way. Your IC actions have IC consequences. If your character decides to become the Butcher of Bakersfield
then he's welcome to go ahead. Just remember that you - the Player - can't come back complaining to the GM when the City Watch decides to shoot him on sight.
I was referring more to the idea that a game system can accurately model physics and what not.
As to genre, I am looking at an existing civilization that has myths of a bygone era where man had the power of the gods until he awoke the demons. They came into our world and the old civilization descended into madness and death. The demons are mostly gone now but a few are still around.
PC's would be those hired to search out the old ruins and see if any of the artifacts still work and then bring them home to their town/kingdom or perhaps sell them to the highest bidder.