When Jonathan Lynn was summoned to Hollywood to write the screenplay for  Clue , his first reaction was that it was the silliest idea he’d ever heard. A feature film based on a board game? But he’d never flown first class before, and he had a spare week. So he went. Forty years later, the film is a genuine cult phenomenon — performed live by shadow casts the way  Rocky Horror  once was, endlessly rewatched on streaming, and quoted with near-religious devotion by multiple generations of fans. On the latest episode of  It Happened in Hollywood , I sat down with Lynn for a wide-ranging conversation about how one of comedy’s most intricately engineered films came to exist. (It very nearly didn’t.) Lynn arrived in Los Angeles as the sixth writer to be approached about the project — after Tom Stoppard, who accepted the commission and then mailed back the check with a note saying the whole idea was hopelessly old-fashioned.…