Thankfully we were spared an awful sequel that might have destroyed our perception of this wonderful classic.
Steven Spielberg's original concept for the movie was the story of a family that was terrorized in their home by aliens. He instead decided to go with a family-friendly movie and the family-in-jeopardy concept was developed into Poltergeist.
Most of the script was written while filming Raiders of the Lost Ark. Spielberg dictated the story to screenwriter Melissa Mathison, who was the then-girlfriend and future wife of Harrison Ford.
Via: collider.com