SURPRISE, surprise, a new marketing strategy has come into the chameleon world of Cantonese films: the hour-long movie. Unlike its 90-minute cousin, the new marketing ploy from Raymond Wong's Mandarin Films has taken to making 60-minute blitzkriegs packed with the obligatory violent scenes. Ms Roberta Wong, distribution manager for Mandarin Films, said the new 60-minute film Insanity, starring Simon Yam and Chow Hoi-mei, was a guinea-pig to determine whether the concept would be accepted by film-goers. ''This thriller type of film is suitable to have a running time of around 60 minutes. That way we can compress all the action and excitement, and make a really thrilling film,'' Ms Wong said. ''This is just the first picture. We'll wait and see what the reaction from the audience is like before we decide to make any others.'' The concept of an hour-long film originally came from Japan with its huge success in short action cartoons. Now in Ho ngkong cinemas, the short film can have about nine sessions a day with a reduced price of about $26, compared with the the $30 to $40 admission price for the longer films. With Hongkong's business-like attitude towards entertainment, the short film idea should be successful. ''If it is successful the higher box office takings will help us make even better, higher budget films,'' Ms Wong said. The basic production costs between the two film types are similar. But there were other avenues where Mandarin Films would increase spending, Ms Wong said. ''It's in post production that we are starting to expand. Like sending the films overseas for better sound and film quality.'' With its changing trends, Hongkong's films could be on the verge of another cycle which is sure to please the Canto-film fans.