Round 1: Genre SaladBut Hong Kong isn't Hollywood, and that's the first thing that makes these movies so awesome from the perspective of an average American guy who grew up with Hollywood's formulas.
You'll find movies that will seem at first like horror movies, or romantic comedies, but don't worry! They quickly turn into a lovely and confusing bastard hybrid of genres that is much, much stranger, and more wonderful. Where else can you find a serious, sappy, sentimental, violent, action, buddy film, with what-the-fuck cinematography, stylized gun-play, and unlikely kung fu? Where else can you find a horror, comedy, romantic, new year's, suspense drama with well-choreographed fight scenes? And musical numbers?!!
There are good reasons for this genre salad: Chinese culture has its own deep and rich cultural history with very different kinds of stories than you find in Western culture. Hong Kong film makers are steeped in this culture, and draw heavily from this culture, but they also attempt to position their films for an international audience that was mostly familiar with Hollywood. Add in Hong Kong's liminal status as a British colony during its film heyday, and you have a recipe for amazing cultural hybrids.
But the bottom line here for the Western movie fan: Prepare to be amazed at what film genres can do when they leave the safe confines of Hollywood!
Round 2: Weirder Established GenresWhat emerged are a set of genres that are distinctly Hong Kong. But they are much weirder than boring old Hollywood genres, and therefore much more interesting and refreshing.
For example, Hong Kong cinema has established genres like Hopping Vampire movies. Try to find “Hopping Vampire” on Netflix's genre list, or on a shelf sign in your local video shop.
And it gets better. Just like in Hollywood, these genres have sub-genres. Except in Hong Kong, the sub-genres are things like Baby Hopping Vampire movies, Musical Hopping Vampire movies, and Exploding Hopping Vampire movies. Seriously.
Round 3: Hong Kong Filmmakers Kick AssThe most important thing that makes these movies so cool is that Hong Kong totally kicks Hollywood's ass!
Especially in its heyday in the '80s and '90s, Hong Kong film makers were far more adventurous, far less restrained by convention, and much more willing to take risks than their Hollywood counterparts.