While Western exploitation films of the 1960s and 70s – gory, sex-crazed shockers such as Herschell Gordon Lewis’ Blood Feast (1963) and Russ Meyer’s Faster, Pussycat! Kill! Kill! (1965) – were largely confined to low-rent drive-in cinemas, Hong Kong took a decidedly different approach.The introduction of the Category III rating in 1988 gave rise to an adults-only genre that did not just lurk in the underground – it conquered the mainstream.Although local martial arts films had been marketed on their violent content since the late 60s, exploitation films proper did not make an appearance in Hong Kong until the early 90s, following the introduction of the new classification.Category III marked the first time the city had an adults-only rating for films. Previously, movies were open to all ages. The new rating led to an explosion of films featuring soft-core sex, gore and extreme violence.Movies such as Sex and Zen (1991), Dr Lamb and Naked Killer (both 1992) and the notorious The Untold Story (1993) dared to go where no Hong Kong film had gone before – and, for a few years, audiences loved them for it.Amy Yip in a still from Sex and Zen (1991). Photo: Golden HarvestMost of these films look shoddy today, and a few, such as the misogynistic Dr Lamb, which features necrophilia, are as repulsive now as they were back in the 90s. In retrospect, the Category III phenomenon is more notable for its unique social characteristics than for its cinematic qualities.