Concept Art featuring Ryan Green and his son Joel from the video game “That Dragon, Cancer” (That Dragon, Cancer, courtesy of the filmmakers)

There’s a scene in “Thank You For Playing,” a documentary about death and video games, where game developer Ryan Green stood quietly in the middle of PAX, an enormous gaming conference. All around Green and his team, clusters of gamers wearing headphones tried out new first person shooters. Each player was in a violent world, playing to survive in their own way. But the people trying Green’s game were experiencing something different. Instead of another player, a zombie, or an artificial intelligence, the villain in his game is represented by the dark silhouette of a bare tree. It is the cancer that would eventually take the life of Green’s young son, Joel.

At that 2013 conference, the players who tried a demo of “That Dragon, Cancer,” walked into a quieter, darkly lit room at the convention. On the desk was a lamp, box of tissues and a framed photograph of Green and Joel, who was 4 years old then. Green’s entire family voiced their own characters in the game. When you play with Joel on a bouncy horse at a playground, it’s really him saying “Go!” and really him laughing as he gallops in place. It’s not Joel, however, when he’s upset and wailing. That would have been too much.

As they played, many began to cry.

“A woman was sitting there, pushing Joel on the swing,” said Malika Zouhali-Worrall, one of the filmmakers who spent 14 months on and off filming the Greens for the documentary, which will air on PBS on Monday night. The woman kept pushing Joel in the game on that playground, over and over. Was she okay? the game team asked. She was, she said, she just wanted to stay there for a little while.

The filmmakers heard about Green’s project from a small write-up of the indie project on Killscreen. At first, it was the art that struck them. “The first image I remember seeing is Ryan, the avatar, and his son Joel, in a hospital, and there’s this twisted tree growing behind them,” Zouhali-Worrall’s co-filmmaker David Osit said.

He added: “We were interested just as much in the idea of what it’s like to make this art for the family in the first place, as what it would look like.” The resulting film documents the decisions Green and his wife, Amy, make about how to tell their son’s story — and how the deeply Christian family reconciles their prayers and hope for a miracle with Joel’s eventual death at age 5.

The result is a brutal and beautiful game that doesn’t leave you.

It’s not the first video game to explore issues such as death, faith and despair in a meaningful way — Zoe Quinn’s “Depression Quest” comes to mind, for instance, as does “Gone Home” to some extent. What “Thank You for Playing” shows is just how much work it takes (professionally, emotionally, everything) to put a game like this out into the world, sometimes in ways that even the Greens didn’t expect.

“This isn’t something you just lob into the world and let go,” Green said in an interview. “This is something you have to handle with care. I wanted to be willing to be there and talk to them and own up to the fact that we did this. And to be there for them to share their experience.”

“There’s a sacredness to that,” he added. “It just felt like the right thing to do to go there and share it with people.”

Sure, the game team and the filmmakers expected an emotional reaction to the first demos of the game. The tissue box was there at the demo station for a reason. But what was surprising was the depth of it. People were leaving the game, walking up to Green, and pouring out their own stories about personal illness.

“A lot of times, our culture wants to take away pain. That’s our natural inclination. They want to offer a fix, they want to offer a reason,” Green said. What he experienced putting this game out into the world showed him that there is a “hunger in our culture to acknowledge our pain, and try to not take it away.”

“That Dragon Cancer” is itself a documentary, Osit said, one of many ways that the Greens chose to document Joel. Amy Green kept a popular blog about their family as her husband worked on the game — her posts were incorporated into the game as letters. And then there were Osit and Zouhali-Worrall, invited to spend time with the family before and after Joel’s death. The documentary contains the changing meaning that the game had for the Greens as it, and Joel’s illness, progressed.

Green told me that he thought he should be present at the first demos because he was asking so much of the players. This was the best thing he could do to try to earn their trust, to convince them that Dragon Cancer requires players to open themselves up to emotions that aren’t usually a part of the typical video gaming experience. And he’s right, it’s a lot to ask.

In “Thank You for Playing,” the cameras followed one young man at PAX. He entered and played. Then he took off his headphones, walked out to Green. “Thank you,” he said, reaching for a handshake. They hug instead.

“Take care.”

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