"When shooting ads, we have to tell a story within 30 seconds," Fatball says. "Every frame of picture has to be informative and interesting enough, and we use that skill in The Gutter.

"We don't want to repeat ourselves, but one thing is repeatable: to tell stories of human nature, be it a comedy or a horror. They're just expressed in different ways."

Yeung says there is another thing that will remain unchanged-the production team working well.

Norris Wong, screenplay of Margaret & David: Green Bean, joined the duo again to write the story of The Gutter.

"We don't want the story to be overwhelmingly 'dramatic', but to simply reveal family ethics," Wong says. She had concerns about the drama due to its unique format, so its success turned out to be "a surprise".

"I often read reviews on Douban, and I've found that viewers are really careful about details," she adds.

Details are vital. For example, as the plot unfolds, memories of different characters differ not just about events but also on items of clothing. That also makes watching the series seem, at times, like a spot-the-difference competition.

Despite the creative approach, Wong admits that they used some well-known plot devices, which may run the risk of being "cliches" but may make characters feel emotionally approachable.

"We still have someone falling ill in the series, some eavesdropping, some misunderstandings, and many story devices that get used in other TV series, but the recipe is not the same," Wong says.

For fans growing up in the 1980s and '90s, watching Hong Kong classics, many still find an outlet for their nostalgia. Veterans like Paul Chun, 75, and Lau Siu-ming, 89, have also joined the cast, as did some stars who experienced the "golden age" of Hong Kong dramas with local television broadcaster TVB.

Bowie Lam, 55, who plays Thomas, also a producer of The Gutter, said in a previous group interview when the series was launched: "Telling a good story matters… We haven't thought too much about the tastes of those people who grew up watching TVB-style productions. I don't say they were not good, but it's time to embrace the future."

Both directors mention that cooperating with online platforms from the Chinese mainland, like Youku, will provide more opportunity for Hong Kong scripts to be turned into productions.

"Online platforms bring us a larger space to create more varied content," Yeung says. "We have all kinds of possibilities in the big market."

And a wider horizon is probably what the directors have given to The Gutter.

Despite being inspired by the shared popularity of the series on the Chinese mainland and in Hong Kong, Yeung says he does not cater to any single market, but explores common emotions that can travel around the world.

"Hong Kong is a very small place, but we want all people to be able to relate to the stories. We seldom create stories that feel 'local', and all our stories will eventually be about inner worlds," Yeung says.

Wong believes the art-house approach of The Gutter may provide a possibility for other directors to try new ideas instead of sticking to tried and tested but "safe" themes, such as those of police officers or lawyers.

The Gutter, successful as it is, may not represent a new page for Hong Kong drama, Fatball says. "But more can be achieved by Hong Kong directors if we are given more room for creativity," he adds.

Yeung agrees: "Someone has to take the first step. Even if it's a detour, it at least explores an unknown area. I will be happy if more people follow."