Prior to Christopher Nolan launching Batman Begins in 2005, Frank Miller collaborted with Darren Aronofsky for a different Batman movie.
The project got so far as concept art and a script was created, but Miller reveals why WB put a stop to it -- citing it was too dark and not what they had in mind (via THR):
It was the first time I worked on a Batman project with somebody whose vision of Batman was darker than mine. My Batman was too nice for him. We would argue about it, and I'd say, "Batman wouldn't do that, he wouldn't torture anybody," and so on. We hashed out a screenplay, and we were wonderfully compensated, but then Warner Bros. read it and said, "We don't want to make this movie." The executive wanted to do a Batman he could take his kids to. And this wasn't that. It didn't have the toys in it. The Batmobile was just a tricked-out car. And Batman turned his back on his fortune to live a street life so he could know what people were going through. He built his own Batcave in an abandoned part of the subway. And he created Batman out of whole cloth to fight crime and a corrupt police force.
The article also suggested that Miller turn the project into a graphic novel, in which Miller doesn't think that is a bad idea.
Maybe I will.
Check out the concept art: