“High concept” is a cynical film meta-genre which first appeared in the late seventies of the last century.
“Meta-genre” means that such films can belong to any known genre while remaining high concept at the same time.

High concept is cynical because its creators make informed predictions on likely emotional reactions of their prospective audiences and tailor their product accordingly, whilst the audiences pay to experience the predicted emotions without sharing the knowledge of what they are likely to be. The film-makers bank on their predictions coming true, and, by and large, they do.

A high concept film will have a simple plot, with a clear storyline propelled forward by every available element of the film’s structure and usually stretching over several full feature length episodes. It will belong to a clearly identifiable genre, such as science fiction, horror, thriller, war, fantasy, sword and sorcery and so on, and will consciously respect the conventions of that genre. It will have high production values, a polished, finished look and will, even when it takes place in the desert during World War Two, rely heavily on special effects. It will have a logo-type title and the same opening musical theme in every episode, both (re)introduced, as we have already seen, by Star Wars whose Episode IV: A New Hope was arguably the first high concept film in the full sense of the term.

Why “reintroduced”? In the fifties, there were film serials such as Flash Gordon or Lone Ranger or Zorro. Television took that format over later. One could see those serials as prehistory of high concept. Lucas did: it was one of the ready-mades he used.