Sleeping Dog‘s Zodiac Tournament DLC is the game’s second story-based expansion and is due for release tomorrow on the 18th. It sees Wei Shen as he goes undercover in an Enter The Dragon style fighting competition.
The add on includes a new area in the shape of a Hong Kong island filled with fighting arenas. As you battle various fresh enemies and bosses there are special moves to be unlocked as well as a couple of outfits.
Apparently there is a suggested level requirement for the content and the game will advise you if you should maybe play a bit more of the main game first.
Source - OPSM