Matt Damon and Ben Affleck had their own Whitey Bulger movie in the works before Black Mass beat them to the punch and while doing rounds promoting The Martian, Damon let us know what their Bulger movie would have been like. While working on the story, Damon got a letter that kind of changed the direction of the film where they wanted to take a different approach.
Via Boston Globe,
“Ben and I had an idea that we would do it more like Unforgiven — which was the anti-western. We wanted to do the anti-gangster movie,” Damon revealed. “If we make it about our own complicity — like why do we celebrate this sociopathy, then that’s a place that hasn’t been mined … and it’s really interesting.” – Matt Damon
Damon went on to say that the story could actually be made into a different film that didn’t have to be about Whitey Bulger as he doesn’t know if their should be a second telling of the story. Can’t have too many gangster films. Bring it on.