"RoboCop" was considered easier to merchandise than other R-rated films. Despite its violent content, film merchandise was targeted at a younger audience. Merchandise included cap guns, comic books, other assorted toys, theme park rides, novels, and the RoboCop Ultra Police action figures (released alongside the 1988 animated series adaptation "RoboCop"). By the time of the film's release, Marvel Comics had published a black-and-white comic book adaptation of the film, without the violence and adult language; a video game was in development; and negotiations were underway to release t-shirts, other video games, and RoboCop dolls by Christmas. The film's poster was reportedly more popular than the "Sports Illustrated Swimsuit Issue"; and its novelization, written by Ed Naha, was in its second printing by July. Since its release, "RoboCop" has continued to be merchandised, with collectible action figures by the National Entertainment Collectibles Association, Hot Toys, Sideshow Collectibles, clothing, and crockery. A 2014 book, "RoboCop: The Definitive History", details the making of the "RoboCop" franchise.