A decade ago, an emotional and nostalgic show about life in 1980s Seoul launched. It had a huge impact both at home and abroad, paving the way for other Korean global hits like Squid Game.

"The most important thing in my dramas is the people who share time and space," says Shin Won-ho, director of hit South Korean series Reply 1988. This focus on connection is apparent from the show's first episode – which aired 10 years ago this month on Korean cable network tvN – when we meet teenage slacker Sung Deok-sun (K-pop star Hyeri).

With her tight-knit community within Ssangmun-dong rallying around her, she prepares to carry a banner for Madagascar – as a "picket girl" – at the opening ceremony of the 1988 Seoul Olympics. Thrilled as Ssangmun-dong's adults are with Sung Deok-sun, her childhood friends are mostly unmoved. At a watershed moment for South Korea, with the Olympics putting the eyes of the world on a country enjoying newly established democracy after decades of dictatorship, Deok-sun and her peers are more focussed on turning 18.

Tracing their transition to adulthood from the summer of 1988 through to 1995 – particularly their first loves and family dramas – Reply 1988 presented a relatable set of characters and storylines that resonated so strongly in South Korea that it changed the landscape of modern Korean television. It not only ushered in South Korea's cable era but laid the groundwork for a swell of more realist and nostalgic Korean dramas – or K-dramas, as they have come to be known – from Hometown Cha Cha Cha to Crash Landing on You. And its global reach opened the door for other K-dramas, including Netflix phenomenon Squid Game, to attain international success.

It's a drama which, among other things, is a powerful reminder of the joy of youth. While the older characters worry about money, wring their hands over student protests, and reckon with what a changing Korea means for their children, Deok-sun and pals cluster on each other's bedroom floors to bicker over the last slice of pizza. They navigate the choppy waters between childhood and adulthood by watching and rewatching John Woo's seminal 1986 action film A Better Tomorrow; they dance, read manga, and – in the boys' case – obsess over actress Lee Mi-yeon (who, in a meta twist, plays an adult Deok-sun in flash forwards to the present).

"I strive to make [series] many can resonate with – [which help us] remember how we have lived, how we have formed relationships and cared for one another," Shin tells the BBC. "So that we can share even a small piece of solidarity." It's been a decade since Reply 1988 did just that: brought audiences in South Korea and subsequently around the world, together in a collective nostalgia for a pre-online world that feels increasingly out of reach.

"[South] Korea's content industry at the time [of Reply 1988's release] was primarily a legacy media-based environment centred around the big three broadcasters," Shin says. Cable television had experienced success before, including with previous entries in the Reply series: 1997 and 1994. But none had rattled the domination that terrestrial networks KBS, MBC and SBS exerted over South Korean airwaves like Reply 1988, blazing a trail for cable series to have much greater impact.

A remarkable 19.6% of viewers tuned in to discover who Deok-sun married in Reply 1988's finale, making it the most popular cable programme of all time in South Korea. "What made the achievement even more remarkable," adds Lee Yoon-seo, The Korea Herald’s drama and streaming entertainment correspondent, "was that Reply 1988 succeeded not........

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