Resulting from events that occurred in 1931 surrounding Irving "Kid" Tannen and his sons Biff, Cliff and Riff Tannen. What normally would have been bullying on the part of Biff was transformed into a crime syndicate of beatings and scaring of residents out of Hill Valley. The family crippled George McFly, leaving him paralyzed and in a wheelchair since at least 1968, making his wife Lorraine distraught, while their children Dave and Linda fled. The Marty McFly of this timeline left Hill Valley in 1984 on the condition that the Tannen Crime Family left George and Lorraine alone. As their reign of terror continued, they made allies with other crime families, most notably the Sacramento Mob, of which J. J. Valenti gave them a personalized Gun Lighter as a gift.
Marty McFly (from the original timeline) returned to 1986 thinking things would be normal again, but only found the three Tannen siblings at his parent's house, ready to fight him. Marty fought them off temporarily, only to find himself at the end of Old Kid Tannen's pistol. Luckily, Doc pushed the DeLorean into the back of Kid's vehicle and saved Marty. The alternate timeline was erased once Doc and Marty returned to 1931 and interfered with events favoring Kid Tannen's success.
- Back to the Future: The Game
- Back to the Future: The Game - Episode 2: Get Tannen! (First appearance)
- Back to the Future: The Game - Episode 3: Citizen Brown (Mentioned only)
- When asked when he was ran out of town, Cliff mentioned that he left two years ago.