For a half-century, almost the complete history of the feature film, the most reliable and prevalent genre was romance, either comedy or drama. Hollywood did make science-fiction films in the years just before Star Wars but they were mostly of the dystopian variety — Planet of the Apes, Logan's Run, Soylent Green, Lucas' own THX-138 — and carried grim political or ecological messages. The more innocent science fantasy, familiar from 30s-40s B-movie serials like Buck Rodgers and Flash Gordon, was not big at the time. Star Wars made it hot, and made it an A-movie genre (though directors like Ridley Scott, in Alien and Blade Runner, quickly reimposed the dystopian tone). Further, Star Wars' exaltation of the movie-serial/comic-book impulse reverberates in every Marvel movie spinoff. That's why, reversing another longstanding trend, more big movies today are made from comic books than from best-selling novels.