From the instructions:
Get 'Back to the Future' in this exciting race against time.
You are Marty McFly, a High School Senior who has travelled back in time to 1955 in an amazing sports car time machine built by your friend. Dr. Emmett Brown (or 'Doc'). Unfortunately, you have prevented your parents, now teenagers, from meeting and unless you arrange for them to fall in love, you and your family will cease to exist!
The lead C64 version was designed by Mark Eyles and programmed by Martin Walker. The game was originally published by Electric Dreams. It was converted to the Amstrad and Spectrum by Software Images.
The object of the game is to get Marty's parents to fall in love through collecting objects in the game - Love poems, cups of coffee, Marty's guitar, etc. Each item has a different effect on the other characters in the game.
Photographs in the corner of the screen indicate progress. Completing activities that make Marty's parents spend time together will add segments to the family photograph. However if the photograph disappears, it means that Marty has failed!