Fallout has a lot of iconic hallmarks—ghouls, deathclaws, radioactive cesspools, and some swingin' music. But it's also iconic for the Vault-Tec Assisted Targeting System (VATS), which sees you using your Pip Boy to target and pop-pop body parts of various wasteland uglies.
While it'd be hard to think of a Fallout game without VATS underlying it, linking gunplay to the classic RPG elements of its predecessors, Fallout 3—the first Fallout game after Bethesda acquired the licence—almost threw the gunplay out with the… uh, gunwater. I've lost track of this metaphor.
