A red herring is a plot device that is meant as a distraction by turning focus away from the truth. It may take the form of a false clue or the emphasis of another character. Once unveiled, a red herring is generally of little use to the rest of the story, as its purpose has already been served.
Examples in Video Games
Shin Megami Tensei: Persona 4
Several red herrings exist in the story of Persona 4. During the course of the murder investigation, the trail leads to the high school student MItsuo Kubo as the supposed culprit of the Inaba serial killings. However, it is later revealed that he didn't kill either of the first two victims and only played copycat when he murdered Kinshiro Morooka. The actual culprit uses Mitsuo as a cover in order to continue his game by throwing both the protagonist and his friends as well as the police temporarily off the trail.
However, there's an even greater red herring at work. It is initially presumed that Ameno-Sagiri is the source of the events that had transpired in Inaba over the course of the year, and that everything will return to normal with his defeat. Instead, Ameno-Sagiri is himself only a servant of the true culprit, Izanami.