The “extra life” was a fixture of early video games, a reward for skilled players that was imbued with the language of reincarnation. Players would not say they earned additional time to play, or a bonus turn, upon reaching a certain score. They were bestowed an extra life, a new chance at existence.

Death is not so frivolous in That Dragon, Cancer, a video game about Joel Green, a terminally ill 5-year-old, and his parents, Ryan and Amy. It is a game about a single life—one that ends and then is gone forever.

The Greens, who live in Colorado, spent the past three years making the game with a small team of artists and designers. Ryan Green, who is a programmer, quit his job to work on the project. It is based on their own lives and that of Joel, who died while the game was in development.

That Dragon, Cancer is not the first memoir to arrive in the form of a video game, but it is probably the most ambitious. “I feel like That Dragon, Cancer is one of those breakthrough moments,” said John Sharp, a professor of games at the New School and the author of Works of Game, a book about the intersection of games and art. “I think we may look back at this game and see this as a touch point, a moment of rethinking what people can do with interactivity.”

That Dragon, Cancer mixes animation and magical realism to convey the Greens’ emotional state during Joel’s illness. There is one dragon, but much of the game consists of re-enactments of mundanities like phone messages and hospital visits. Water fills a room as a doctor says there are no more treatments for Joel’s cancer.

The game also uses documentary audio—taken from home movies as well as from Thank You for Playing, a film about the Greens that had its premiere last year at the Tribeca Film Festival. Players hear Joel’s laughter, and they listen to the prayers that his parents, who are Christians, shouted on the last night of Joel’s life. The interactions offered to the players of That Dragon, Cancer are relatively limited. Players mostly click to decide which part of a vignette—feeding ducks at a pond or escorting Joel through a playground—will unfold, and when to move on to the next part of the Greens’ story.

The restricted controls are intentional. A go-kart race through a hospital frustrated some critics, Green said, because the unwavering speed of the go-kart is dictated by the game. “That’s the point,” he said. “All you can do is steer, hopefully.”

Withholding some control from the player was an attempt to convey feelings of helplessness and despair. “One of the great strengths of video games is that automatically a player goes into a game expecting to have some agency,” Green said. “And it felt like the perfect way to talk about cancer, because all a parent wants is to have some agency.” A closer antecedent may be Jason Rohrer’s Gravitation, released in 2008. The pixe

l art in Gravitation is playfully retro, but the representation is real. The player controls an avatar meant to resemble Rohrer, who can play catch with his son or—during bouts of creative mania—abandon him.

“Instead of just showing a character grappling with a difficult situation and seeing the choices a character makes, you can give the player a difficult situation and let them grapple with it themselves,”  Rohrer said of his game, which takes eight minutes to complete. Rohrer also mentioned dys4ia, a 2012 web browser game, as a landmark among video game memoirs. It is by Anna Anthropy and is about her decision to begin taking estrogen for hormone replacement therapy.

More video game memoirs have come since, including Nina Freeman’s Freshman Year, about sexual harassment at a college bar, and a flood of interactive fiction written using the software Twine.

Other games may allude to, or allegorise, the designer’s life story. The Legend of Zelda, the 1986 Nintendo game, is said to have been inspired by Shigeru Miyamoto’s youthful exploration of a cave northwest of Kyoto, Japan. Adr1ft, which will be released next month for the Oculus Rift, Facebook’s virtual-reality headset, is an outer-space adventure inspired by its designer’s public shaming on Twitter. Unlike these games, a true video game memoir presents itself as nonfiction, even when it departs from the literal.

Sharp of the New School compared the cultural status of games in the early 21st century to that of painting during the Italian Renaissance, when it began to shift from being a functional tool to a purely aesthetic form.

“It took hundreds of years to make this transition for painting,” he said. “So, looking at it through my art-historian goggles, it’s not really a surprise that there are folks who are outside the epicenter of the games community who make the assumption that if games aren’t escapist, they must be educational or therapeutic.” Outsiders are not the only skeptics. Many of the most devoted video game players have resisted the expansion of the medium into new forms like memoir, said Vander Caballero, the designer of Papo & Yo, a 2012 PlayStation game about his relationship with his alcoholic father.

In Papo & Yo, Caballero’s father is represented as a monster who becomes violent when he eats frogs. Rather than defeating or curing the monster, players learn to live without him. “We have proved that we can tell these stories through game design,” Caballero said. “But we haven’t proved that you can be profitable.” Despite all the attention paid to That Dragon, Cancer—-podcasts, magazine articles, a documentary film, millions of YouTube views of people playing it—the game’s sales in its first month have been modest, the Greens said.

About 10,000 people have bought it, according to the website SteamSpy. That’s a nice number for a work of creative nonfiction that arrives inside a dust jacket, but not for a three-year software project with eight people working on it.

“I always tell people, ‘You know those indie, artsy films that Ryan likes and no one else likes?’” Green said. “‘There are video games like that.’”