Not wishing to feature the Nazis as the villains again, George Lucas, executive producer and co-writer, decided to regard this film as a prequel. Three plot devices were rejected before Lucas wrote a film treatment that resembled the final storyline. Lawrence Kasdan, Lucas' collaborator on Raiders of the Lost Ark, turned down the offer to write the script, and Willard Huyck and Gloria Katz were hired as his replacements, who had previously worked with Lucas. The film was released to financial success but initial reviews were mixed, criticizing its dark tone. However, critical opinion has improved since 1984, citing the film's intensity and imagination. In response to some of the more violent sequences in the film, and with similar complaints about Gremlins, Spielberg suggested that the Motion Picture Association of America (MPAA) alter its rating system, which it did within two months of the film's release, creating a new PG-13 rating.