Engelbrecht, who is 42, grew up outside Syracuse, New York. As a kid, she coded fortune-telling programs on her parents' Texas Instruments computer and enjoyed games like Oregon Trail and Zork, which she played with paper and pen so she could track and draw the maps. “You'd have the best of both worlds, where you'd get to read and also interact,” Engelbrecht says. She remembers her enthusiasm for the 1985 mystery film Clue, which has three different endings.

The novelist Yiyun Li has written that her motivation for reading fiction is “to be with people who, unlike those around one, do not notice one's existence.” Engelbrecht, however, has never required such distance. Her style may align more closely with that of Julio Cortázar, the Argentine author of such experimental works as Hopscotch, who said that “literature is a form of play” and should aspire to be a game both “profound and serious.” Even when Engelbrecht was young, the boundary dividing characters from viewers seemed a little porous. “My mom referred to soap operas as ‘I'm watching my characters!’—it was a relationship,” she says. She felt a version of this herself, wondering, “What is my relationship with the story?”

Engelbrecht's work in interactive TV could—if viewers play along—chart a course for how Netflix stays relevant and designs ever more bingeable stories.

At college, where Engelbrecht studied political science, she gravitated to journalism, later applying for jobs at National Geographic, Motor Trend, and Highlights for Children. She landed at Highlights, a monthly publication whose mission is to “help children become their best selves.” Engelbrecht sees her time there as “this world of play,” she says. As part of the job, she'd go into schools and watch how kids interacted with media. She took those observations to PBS Kids and Sesame Workshop and eventually to a doctorate program in education at Columbia University, where she studied the social dynamics of videogame usage. Before graduating, she founded a game design consulting firm, No Crusts Interactive, which helped create four Sesame Street games. (She has never managed to dislodge the Elmo song from her head.) Around that time, Engelbrecht met with Todd Yellin, VP of product at Netflix, for a possible job. During the interview process, they talked about the possibility of pursuing interactive stories.

In 2014, Engelbrecht joined Netflix as the manager of kids' products, combining her interests in game design and education. She saw Netflix as a giant system to be interacted with, and she and Yellin started experimenting with nonlinear, or “branching,” shows for children. “We knew if we couldn't make this work for kids, it would never work for adults,” Engelbrecht says. “There's a more inherent willingness to interact in kids,” who are often better versed in typing and swiping. Over the following years, Engelbrecht and Yellin rolled out a series of interactive shows for children and young adults: Buddy Thunderstruck: The Maybe Pile; Puss in Book: Trapped in an Epic Tale; and, most recently, You vs. Wild, a reality show in which you try to keep professional adventurer Bear Grylls alive. Though viewers can passively let the programs make choices for them, Netflix says 94 percent of You vs. Wild and Bandersnatch viewers took an active role.

According to trends Engelbrecht has gleaned from Netflix's research, parents enjoy watching their children consider the ramifications of their decisions. A child who's tempted to make a choice that provides some thrill or gross hilarity—force Grylls to eat poo, say—might then display concern, electing to have Grylls go foraging instead. Much as the woman in Phoenix had wanted Stefan to succeed, both children and adults seem to feel sympathy for the characters whose lives they momentarily control. In some cases, Engelbrecht has also noticed more of a willingness to act out, an approach she refers to as “vicarious catharsis.” Certain adults, steeped in the twin enticements of videogame-like joy and a momentary reversion to childhood, savor the chance in Bandersnatch to make a choice between “kick him in the balls” or “karate chop the dad,” she says.