Then I saw the teaser a second time and had my suspicions confirmed. There amidst all the credits it said based on a story by Akira Kurosawa. To do so means to kill off the rival mob.
Problem is both mobs are pretty equal and end up destroying more town than each other.
Enter Bruce Willis, an opportunist who exploits both sides for cash. Eventually saving the town by cleansing out the mobs entirely. Everybody who really deserves it gets it in the end. For those who like action flicks this is your stuff. The story is simple and its predecessors are well liked in cult circles.