Warning: Spoilers for Squid Game

Squid Game star Lee Jung-jae reveals which of the show’s deadly games were most difficult to film. A survival thriller created by Hwang Dong-hyuk, Squid Game focuses on deeply indebted individuals that compete in fatal variations on children’s games for a big cash prize. Netflix announced that Squid Game has bested Bridgerton, nabbing 111 million viewers worldwide in the first weeks of its release. Given its impact, many have wondered why this particular iteration of the death game genre has resonated so much with audiences.

One reason has to do with the performances of the cast. Along with Lee, who plays Gi-hun, and functions as something of an audience surrogate throughout, Squid Game features a talented ensemble that includes Park Hae-soo, Wi Ha-joon, Jung Ho-yeon, O Yeong-su, Heo Sung-tae, Anupam Tripathi, and Kim Joo-ryoung. Another has to do with the writing, which serves partially as a commentary on class divisions and unfettered capitalism. But a big part of the appeal has to do with the concept itself, as it’s predicated on the kind of kids play that would be familiar to most viewers. Except, of course, it’s given a lethal twist.

Related: How The 1988 Seoul Olympics Influenced Squid Game

In a wide-ranging interview with EW in which he discusses Squid Game‘s popularity and the potential for season 2, Lee also reveals which of the series’ games were most difficult to film. The actor singles out two competitions, in particular, first mentioning the Honeycomb game. He explained: “I had to express with very minimal movement.” Still, he noted it was that final confrontation between Gi-hun and Sang-woo (Park) that was the most challenging. Lee’s quote is below.

“Because Gi-hun is very hurt because of all these games. And he knows he has to admit the fact that he deceived others in order to survive himself, so he’s very disappointed in himself and in Sang-woo [Park Hae-soo], his close friend, because he betrayed him. These two characters are fighting against each other with their life on the line when they’re childhood friends, so the scene itself is very heartbreaking. It was very emotionally tough. Secondly, I remember that when we were filming that scene when the two were fighting, it was in winter, so the weather was very cold. In Korea the winter is very freezing cold. I remember filming that scene for about four days in the rain with the sprinkler, so it was very emotionally and physically tough.”

Squid Game's cast posing for their promotional poster.

It’s interesting to note that, in his answer, Lee points to what is arguably the most relatively lighthearted episode of Squid Game and then, inarguably, one of the most harrowing. Although it is true that precious little about the South Korean thriller is comedic, getting more dire as it reaches the finale, the Honeycomb stretch occurs in episode 3 and it’s clearly played for humor. Gi-hun and, also Mi-nyeo (Kim) have to use their smarts and think far outside the box to survive. And they do. For a time, things seem relatively hopeful. And then, by the finale, as Lee indicates in his remarks, Gi-hun is just drained of all energy.

It does point to the debate over what Squid Game would look like if it does return for season 2. Will viewers see the same games or will there be others? It’s one of the many questions fans have about the thriller. And, in a sense, it leads to a separate but more significant question about whether the massive Netflix hit would be better off as a limited story rather than continuing to expand its world. Fans disagree on that front, but there’s a consensus that Hwang, and his cast, crafted a tremendous story.

More: Squid Game: Biggest Unanswered Questions & Mysteries

Source: EW