The new teen thriller “Nerve,” which opened on Wednesday, establishes the outlines of its young protagonist’s life in roughly thirty seconds, all of which show her messing around on a laptop. We see her avatar (blond, cute, holding a camera); her name (Venus Delmonico); her choice of Spotify playlist (mournful pop, under the heading “Only Single Friend Left”); and her nickname, via Facebook (where the boy she has a crush on calls her Vee). Vee checks her Gmail: she has been accepted to Cal State. She drafts a reply to the admissions office, confessing that she’s too much of a “spineless loser” to tell her mom she wants to get away from Staten Island. She smashes aimlessly at her keys, frustrated.

Vee, played by a diffident Emma Roberts, doesn’t speak a line of dialogue until her best friend, Syd (Emily Meade), video-chats her, telling her that she just has to sign up for a new game called Nerve. Nerve is a social network that augments and gamifies reality: it’s “Truth or Dare, minus the truth,” according to its welcome reel. On Nerve, there are watchers, who pay, and players, who try to profit. The watchers crowdsource dares for the players, who accumulate viewers and money as they complete a series of increasingly risky tasks. Players record their dares on their phones, and watchers are encouraged not just to live-stream the action but also to provide their own footage—to track the players in real life as they kiss strangers, shoplift, climb buildings, hang one-handed from cranes.

Syd is provocative and bossy—she’s great at Nerve. The game will no doubt make audiences think of Pokémon Go, which also augments reality with digital objectives and has similarly prompted expressions of concern for its players’ safety. Nerve is reminiscent, too, of Twitch, a service that allows people to watch other people play video games. But what it resembles most is Twitter and Instagram: social networks that reward both charm and shamelessness. Syd, when the movie begins, has already acquired a viewership large enough to make a Facebook Live coördinator weep, but that’s not enough: she wants to reach the finals, and so she needs her friends to sign up. “It’s very important that I have watchers,” she says, pouting. Later, at a football game, she opens her phone. “Hey watchers, it’s @sydbaby,” she coos. Then she runs out onto the field in her cheerleader’s uniform and moons the crowd: dare complete.

Vee is eventually goaded into playing, of course, and the watchers pair her up with an impish stranger named Ian, played by Dave Franco. The two then engage in a long series of capers. “Nerve” is based on a young-adult book by Jeanne Ryan, and it eventually caves in under the weight of its gimmick: by the end, what’s keeping Vee and Ian in the game isn’t excitement or romance but a sinister conspiracy—a much less interesting motivation. The film was directed by Henry Joost and Ariel Schulman, who also directed “Catfish,” and who should know that the Internet does not need to be made stranger than it actually is. Social media provides ample proof that people will alter their lives in pursuit of quantified approval, entirely out of their own volition, and for utterly banal reasons—mostly boredom and narcissism. This is what motivates Syd, the movie’s most interesting character. Though she’s arch and distant with her best friends, Syd talks to her watchers as if they were lovers. Online, she’s both intimate and needy, making flirtatious pledges of fealty to her audience. It’s hard to tell who is more dependent on whom.

There are still very few good movies that are centrally about the Internet. Television, with “Black Mirror” and “Mr. Robot,” has more persuasively imagined the Web’s promises and perils. Even on those series, though, there is a tendency to be didactic about the Internet—and a related tendency to reflect online life with a fun-house mirror, to make it ominous and overblown. At its occasional best, “Nerve” functions as a regular mirror, faithfully reproducing the Internet’s patterns of love, hate, and attention. In these moments, the details are sarcastic and eerie, disturbingly mundane. One Nerve user is named “@art_thot69.” The non-stop spray of comments on Vee’s account includes common slurs, comments about her body, jokes about memes. Snapchat clips roll during the end credits; little hearts explode across the screen as the live-streaming numbers go up.

Unfortunately for “Nerve,” Vee isn’t playing for the likes—she’s not out to get famous or attract attention—but, rather, to earnestly prove to herself that she’s not as timid as she seems. The monetary incentive helps. (Her mother, played by Juliette Lewis, is a seemingly overworked nurse.) It also helps that Vee’s initial dares involve kissing Dave Franco, riding a motorcycle into New York City with Dave Franco, and undressing in front of Dave Franco. Both actors are too old for the parts they’re playing, but they have a sweet chemistry: Roberts is best when Vee is credibly delighted by her adventure, when the machinations of the watchers seem, briefly, like romantic fate.

But Vee knows that the game she’s playing is an improbable exaggeration. Her quietly lovelorn friend Tommy (an endearing Miles Heizer) reminds her, “Some kid supposedly died in Seattle playing this.” Tommy explains that the police couldn’t do anything afterward, because Nerve exists on a peer-to-peer network, the watchers are anonymous, and there’s no central server for anyone to shut down. The game’s enticements are ultimately irresistible: Vee joins the lurking faction of people who would make a variety of compromises if the end result were fifty-one thousand people watching them careen through photogenic adventures involving a mischievous dreamboat and glittery couture.

“Are you a watcher or a player?” Nerve asks its users, repeatedly. “I love you so much, Vee, but you’re a watcher,” Syd says. It’s a damning insult for the adolescents of social media: you do the liking; you are never liked.

But all players are, inevitably, watchers, too. Imagining yourself through the perspective of an Internet audience is generally a prerequisite for successfully soliciting that audience. In interviews, the YouTube star Casey Neistat, who makes a cameo in “Nerve,” frequently discusses what he thinks his viewership wants to see. The self, the product, adjusts accordingly; players learn to watch themselves and, in doing so, are doubly incentivized to put on a good show. “The Internet has given me the dopamine, attention, amplification, connection, and escape I seek,” the poet Melissa Broder writes in her début essay collection, “So Sad Today.” “It has also distracted me, disappointed me, paralyzed me, and catalyzed a false sense of self.” And yet, “reality was never my first choice.”

“So Sad Today” is named after one of Broder’s Twitter accounts, which has amassed three hundred and seventy-three thousand followers. She routinely inspires a thousand or more people to retweet depressive epigrams like “i liked you better when you were imaginary.” Broder has “done well at the Internet,” she writes in the same “So Sad Today” essay. “If Twitter is a video game, I’ve beaten it.” The Internet, “even when it sucks, holds infinite potential at all times.”

That’s how it often feels, anyway—and that’s what makes the Internet such a perfect repository not only for our anxieties and fears but for our dreams, too. What “Nerve” catches, in its more realistic stretches, is how the possibility of being seen at all times, by an ever-expanding audience, can narrow our sense of ourselves, even when it’s making us feel expansive. We might learn to want, more than any adventure, the fleeting pleasure of getting people to watch.