The Star Citizen First-Person Shooter Combat gameplay will be revolutionary in many ways. Being set in a persistent open world can mean that a firefight can break out at any point in time, in any situation.
Players are also in space or on a space craft or both, which can have interesting implications to the situation. An evil combatant might shut off the artificial gravity generator onboard a space station and effectively change the firefight into a zero gravity situation. Or a space craft that previously had an atmosphere could have a wall blown open and all of that atmosphere get sucked out and perhaps a player along with it.
A back alley brawl between two rival organizations might break out over a failed black market trade. Perhaps that brawl escalates and spills out into the streets of the planetary port that you are landed at.
Who knows, the possibilities are endless.
The First Person Shooter is still very much under development.