Biffhorrific Hill Valley

The Biffhorrific Hill Valley was an alternate timeline created when an elderly version of Biff Tannen gave a copy of Gray's Sports Almanac to his younger self. This would trigger a multiple sporting event gambling winning streak that would propel Tannen to wealth beyond his wildest dreams. This version of reality was thought to have been erased from existance by the efforts of Emmett Brown and Marty McFly, but continued to exist as a universe paralell to all the others of the multiverse. (Back to the Future Part II, Star Trek: Voyager - Dark Realm)

History
Biff would win his first million on his twenty-first birthday, betting on a horse race in 1958. As he grew wealthier, he developed an eye for the future and created a more stable source of income for himself called BiffCo, a toxic waste reclamation company.

As the CEO of BiffCo and a man of great wealth, he was also a man of great influence beyond the scope of Hill Valley. In 1979 he successfully lobbied to legalize gambling. He financed American president Richard Nixon to a fourth term and was financing his election for a fifth term. A third order effect of this was the fact that the Vietnam War was prolonged past American Civil War

In this reality, Biff was responsible for the death of George McFly in 1973, and married Lorraine Baines McFly after the three kids were born. Hill Valley, now known as "Hell Valley", had been reduced to rubble, where biker gangs and criminals made their home. Hill Valley High School burned down in 1979.

Biff would construct his elaborate residence called Biff Tannen's Pleasure Paradise Casino & Hotel on the site of the courthouse in downtown Hill Valley. He and his wife Lorraine would live, awfully wedded, on the 27th floor of this building.

Marty McFly would discover, to his horror and dismay, that he was responsible for the creation of this reality. He and Emmett Brown endeavored to remove this horrific timeline from reality and apparently succeeded.(Back to the Future Part II)

Continued Existence
Due to the existence of the multiverse, at the time not factored into Emmett Brown's calculations, the Biffhorrific Hill Valley continued to exist as an alternate plane of existence. It was there that Biff Tannen would fall under the thrall of Armus and begin to unite and unleash the Heartless onto the various planes of existance. Thanks to the combined efforts of a stranded away team from the USS Voyager (NCC-74656) and the Institute of Future Technology, Biff's plan would be thwarted. (Star Trek: Voyager - Dark Realm)