Elements from Michael Crichton's novel, "Jurassic Park", were featured in the game, including the presence of procompsognathus and pteranodons, and the Jungle River attraction. The game used the film's original planned ending, in which Grant would eliminate the velociraptors by manipulating a "Tyrannosaurus rex" skeleton in the visitor center. The game's volcano level was not featured in the novel or the film. Sam Powell composed the game's music and sound effects. By June 1993, the development team had been working on the game for 15 months. The game's development had been kept secretive up until that month, when the game was publicly unveiled for the first time at Chicago's Summer Consumer Electronics Show. "Jurassic Park" was the first film-based video game to give players the option of playing as a protagonist or antagonist.