They started appearing outside our kitchen window during the summer, often at dusk, in wary twos and threes: shamblers, lopers, skulkers, wobblers, blipping and tweaking on some new and apparently enhanced neural network. They consulted their phones every few seconds, but they weren’t in full-on, street-oblivious phone mode. They pointed at things (what things?), they got excited, they made little rushes back and forth across the road. Earlier in the year, before all these people began showing up, I’d challenged a man who was standing in the darkness outside our building, motionless, staring at something, a figure of freaky fixity wearing a hat with pulled-down earflaps. When I asked him what he was doing, he turned slowly and—face bracketed by the earflaps—addressed me with icy ceremoniousness: “Do we have a connection?” His question haunted me for days. Had he been some kind of omen or advance guard?

They were, of course, PokéPeople. My 14-year-old son explained it to me. They were votaries of Pokémon Go, on the hunt for low-hanging Pokémon and drawn in shifty clusters to our street corner because (he further explained) it is not a mere PokéStop but a PokéGym: Old Cable Box Gym, to be precise.

If you don’t know about Pokémon Go, I salute you in the splendor of your isolation and beg permission to explain. Downloadable as an app on your smartphone, Pokémon Go launched itself worldwide in July and instantly coated 75 percent of reality with a thin, sticky, brightly colored film of weirdness and distraction. The game uses your phone’s GPS to locate you inside an onscreen map of your environment—you walk down the street, your avatar walks down the street; you turn left, your avatar turns left—and then populates this map with Pokémon, or “pocket monsters”: fabulous animated beings, dropsical-adorable in aspect, from the decades-old, massively successful Japanese gaming franchise. You capture these Pokémon, you train them, they (and you) rise through the levels, and eventually you launch them into bloodless combat with another player’s carefully cultivated stable of bubble-beasties.

The point of the game, its big thing, is that you have to go out into “the world” to play it. A PokéStop is a place—it might be a restaurant, or a park gate—where you pick up the Poké Balls necessary to apprehend your Pokémon. And a PokéGym (represented on your screen as a radiant swirling power-node, fiercely patrolled by upper-level Pokémon) is a site of battle. As you move across the Pokéscape, your phone will buzz—anxiously, ferally—to alert you to the nearby presence of an untrained, or “wild,” Pokémon that you might add to your personal herd. You find the creature on your screen-map, you tap it, point your phone at the corresponding real-world location, and there, there—in your phone’s camera-eye, superimposed onto whatever random sliver of actual life it happens to be looking at—is a perfect, buoyant little Pokémon, blinking at you genially and fluttering its appendages. A Pokémon floating by the mailbox: the real mailbox, in its rusty civic blue. A Pokémon dangling in a bush: a real bush, with leathery leaves and dark city lungs. Hallucinations. Juicy, inviting, bulbously discrete hallucinations. A psychotic break, if you like, for your handheld device.

The first thing to say about Pokémon Go is: Kids, don’t play Pokémon Go. Read Hamlet. The second thing to say is: Wow. I went out one hot August night, late in the craze, with appropriately stuttering tech—my son’s iPhone, cracked screen, dying battery—and caught myself a Weedle, a Pidgey, and a Caterpie. Base-level Pokémon, nothing to write home about, but at the sight of that Pidgey, levitating brightly between a smear of asphalt and a lamppost, I literally gasped. Skunks were abroad that night, large and sumptuously striped real-world skunks shuffling under parked cars with exquisite skunk etiquette, and here—obviously fake, wildly bogus, but no less present to my wondering brain—was this glowing bird-thing.

They call this “augmented reality,” and we’re going to be seeing a lot more of it. The harmlessly bobbing Pokémon, trailing their clouds of gamer nostalgia, are harbingers no doubt of far heavier perceptual tamperings and disruptions. (Zombies. Porn. Snickering mind-gaps to haunt your handheld.) “We came with an idea about seeing the world with new eyes,” says John Hanke, the CEO of Niantic, the creator of Pokémon Go. “The basic notion was there’s a lot of cool history and lore and unknown secrets in your own neighborhood that you don’t know about.” PokéPeople have told me of their enriched attachment to their surroundings, their eyes opened by the game to local curiosities. But later that night, further on in my Poké-odyssey, wandering between PokéStops on an especially dowdy stretch of Boston’s Commonwealth Avenue and peering into the sterile phone-world I was holding in my hand, I suffered acutely from the opposite sensation: that once you’ve bought into the game, once you’re out there on the Pokésavannah, looking for boosted reality, a street devoid of Pokémon is lifeless, and basically pointless.

I thought then of the British writer Iain Sinclair, and something he wrote in last year’s London Overground. The book describes a walk—a plod, a drift—along the route of London’s newest rail network, and at one point (plodding and drifting up the Old Kent Road) Sinclair reflects upon the city’s cyberkids, their tapping and swiping, their heavily interfaced mental environment. “They muddy perception,” he writes, “with pictorial degradation, looped sound, weird fragments … Ordinary working streets, if they encounter them, seem perversely undercooked.” And this was 2015: Sinclair had yet to meet a roaming, jittering, fiending-for-pink-elephants Pokémob.

Sinclair is London’s leading practitioner of psychogeography (although he’d reject the title), the precarious discipline defined in 1955 by the French theorist Guy Debord. Debord needed something, some science or poetics, that could account for “the sudden change of ambiance in a street within the space of a few meters; the evident division of a city into zones of distinct psychic atmospheres; the path of least resistance which is automatically followed in aimless strolls (and which has no relation to the physical contour of the ground); the appealing or repelling character of certain places.” You do psychogeography on foot, like Pokémon Go—but there the similarities end. The psychogeographer rambles, he moseys, undetermined and almost neurotically available to the prevailing vibe. Here he bristles, there he is happily saturated. If he locates a grid, he falls off it immediately. He seeks not Poké Balls but traces, flavors, essences. The goblin particularity of a freshly painted handrail might blow his mind.

What if, by spreading its Day-Glo palimpsest of Croconaws and Pikachus across your local sites of interest, Pokémon Go is actually disenchanting them, draining them of mood and aura? Thirty years ago, in my bland and blameless youth, there was no overlap between games and the world: You played a video game in an arcade, for God’s sake, with clanking buttons, screaming armpits, and coins banged into slots, while the world hummed along outside. The world was something that you reentered, blinking and slightly scorched. With Pokémon Go, the world peeps through the game-layer, uncertain of its own powers—you, meanwhile, are a mighty illusion, stomping around the Poképanorama in your electric boots.

Anyway, now I know that the homely cable box outside our apartment is an interdimensional portal. One evening I saw my friend Dan standing there, phone aloft and glowing in the twilight like some kind of glacial kernel. Dan is younger than I am; he grew up with Pokémon: the game, the trading cards, the TV shows, the movies. Bulbasaurs assisted at the genesis of his imagination as Donkey Kong assisted at the genesis of mine. Now he was at the PokéGym, siccing his obese but battle-hardened Snorlax on a … I can’t remember what. A Slurvert. A Brosupial. An Oblongata. Dan was tapping his screen, an educated frown on his face; the Pokémon were invisibly exchanging their nonlethal rainbow energy blasts; and somewhere in outer space the PokéSong was playing: It’s a whole new world we live in! It’s a whole new way to see! But my reality is unaugmentable. I turn away, I lower my earflaps. Me and Pikachu: Do we have a connection? I think, on the whole, not.