Live By Night, Ben Affleck's 1920s gangster flick, is an ambitious Prohibition-era drama that he directed, starred in and wrote based on Dennis Lehane's 2012 novel of the same name - it is also a passion project he undertook to test himself as a director.

"This was one where I was really trying, as a film-maker, to stretch as much as I could. It was like climbing without a net - it was scary."

That the movie got made at all may be a testament to his clout in Hollywood, where he has become one of the most sought-after directors and stars in recent years.

But it has failed to impress critics in the United States and has earned less than US$10 million (S$14 million) against its US$65 million budget since opening there over Christmas.

Speaking to the press in New York shortly before the film's American debut, Affleck hints he knew doing a period drama was risky, especially given his desire to faithfully recreate the era and channel classic gangster movies of yesteryear.

If this had been his first go at helming a film, he "would have approached it much more safely", admits the 44-year-old, who took home the Best Picture Oscar for his previous directorial effort, the political thriller Argo (2012) and also shares a Best Original Screenplay Oscar with Matt Damon for their feel-good breakout drama Good Will Hunting (1997).

"I wouldn't have been able to do this movie as a first-timer - it was too complicated, too elaborate, there was too much stuff that could go wrong.

"And the only thing that I really was able to coast with was the actors - the rest was a lot of very difficult, intentional work to try and accomplish a classic-looking and feeling movie that I wouldn't have been able to do till now.

"I can see that I wouldn't have been able to make this movie until I had done three other movies."

His early outings as director for the crime dramas Gone Baby Gone (2007) and The Town (2010) were well-received.

This time around, it sounds like his main preoccupation as director was the technical and stylistic challenges of the film, which opens in Singapore today and tells the story of bootlegger-turned-crime-boss Joe Coughlin (Affleck).

He reveals he left the actors mostly to their own devices as a result. "I discovered that I had an amazing cast," he says of co-stars Elle Fanning, Brendan Gleeson, Sienna Miller and Chris Cooper.

"The more I watched it over and over again, the more I was impressed with the people around me, and I can't really take any credit for it - I was so filled to the top with things to pay attention to and was just kind of like, 'Go be in the scene!'

"And I'm watching this work in the editing room later and it was so masterful, so delicate and so specific, I really learnt to appreciate actors even more."

As the story tracks Coughlin's career from Boston to Florida, the director decided he did not want to fake anything, whether it was crowd scenes, exterior shots or car chases, the latter featuring real vintage vehicles that proved temperamental.

"The exterior shots were hard to make because I didn't want to use digital extras - I feel like they're not at the level where they look like real human beings when you stop and look at them. So each of the extras had to have their clothes made and we had to build the sets.

"But I wanted to deliver one of those movies that was like Reds (1981) or Dr Zhivago (1965) - something where part of the spectacle and allure was the scope and scale and the way it would transport you.

"And all the cars are really in the movie," he adds, noting that shifting gears turned out to be a nightmare for actor Chris Messina, who plays Coughlin's getaway driver Dion. "I tried to drive them too and I was a disaster. I don't know how anybody got anywhere," he says, laughing.

When it comes to a scene where Coughlin is menaced by members of the Ku Klux Klan, however, Affleck admits he would have played it differently had he known the hate group would see a resurgence during the recent US presidential election.

"If I knew how timely it would feel, I would've dialled it back, frankly," he says.

"I was surprised to see that the Klan stuff had added resonance all of a sudden. I had put a line in where I say, 'There are five million people in this country in the Klan' because I wanted the audience to understand this was such a different time.

"Obviously, we don't have that now, but it feels a bit like the Klan has more resonance and a bigger presence in this election," he says.

Affleck - who has three children aged four to 11 with his ex-wife, actress Jennifer Garner - says he can see his gradual progression as a film-maker.

"I can see how Gone Baby Gone was a toe in the water, The Town broadened that a little bit, Argo was taking another step, and this is a further step.

"To me, what's important as a film-maker is to keep doing different stuff that interests me and that's diverse. I don't want to end up just being the 'Boston crime guy'."

While he is now in pre-production to direct the big-budget Batman movie and will star in another superhero blockbuster, Justice League, later this year, Affleck says he longs to make smaller films about ordinary people, especially after watching Moonlight (2016), the coming-of-age gay drama that won the Golden Globe for Best Picture (Drama) and has been nominated for Best Picture at the Oscars.

"I was, like, 'This is the movie I should do - a performance movie that's just about someone's life.' It just blew me away.

"And I think my brother (Casey Affleck) is in another great film this year," he says, referring to Manchester By The Sea, a Golden Globe-winning drama produced by his production company Pearl Street Films.

"I often fantasise that me and a couple of other actors would just go take a camera and shoot a movie about the unexceptional life."

• Live By Night opens in Singapore today.