There is already a very good selfmade Unreal Engine Games of Back to the Future like from youtube @moisesnaves. His Creations are showing that graphically it is possible to make a realistic Back to the Future AAA game, which is similar to the movie. This is a private creation from a user that uses Unreal Engine 5. Imagine how it would look like if Universal, Ubisoft or Rockstar Games would be involved. 

In the videos from @moisesnaves on YouTube you can see how great it would look to walk in first person on the Courthouse square of part II and visit places like the Cafe of the 80th. Everything with original music and sounds. You can also drive or fly with the DeLorean - also on the Skyway. Also seeing places the weren't seen in the movies. 

Also possible would be to fly to Marty’s house in the future and then see all the things and people in the house. You could play as Jennifer in the first person perspective, even with the scene where you have to hide in the wardrobe and everything just like in the film. Also visit Alternate 1985, Marty’s home, Biffs Mansion, Graveyard and driving back to 1955 and go to the school and Mr. Stricklands office. Plus every level should also have an open world.

Sign and share the petition on www.change.org/bttfthegame  to make this game finally possible.