ON JULY 10th police in O’Fallon, a Missouri town of about 80,000 people, made a statement about the modus operandi of an armed gang that had been using “Pokémon Go”, a video game, to prey on the locals. “You can add a beacon to a Pokéstop to lure more players,” the lawmen explained. “Apparently they [the muggers] were using the app to locate people standing around in the middle of a parking lot or whatever other location they were in.”

If that sounds like gibberish, it might be best to consult your nearest millennial. “Pokémon Go”, an app for smartphones published by Nintendo, a Japanese video-gaming firm, has proved a smash hit since its release on July 6th in America, Australia and New Zealand. It is the latest instalment of the Pokémon franchise, which began as a video game in 1996, before branching out into collectible cards, toys, books, TV shows and comics, and grossing ¥4.8 trillion ($46 billion) in the process. Players take part in a sort of lighthearted digital dogfighting, in which the protagonists are not canines but cute magical animals discovered and trained by players.

“Pokémon Go” applies that formula to the real world. Smartphones direct players to various locations, either to find Pokémon or useful virtual items (at the aforementioned Pokéstops), or to deploy their charges in battle. An optional “augmented-reality” feature uses the phone’s camera to show a picture of the real world with a Pokémon digitally superimposed (pictured).

There have been unforeseen side-effects, some macabre. As well as the muggings in Missouri, a player in Wyoming found a dead body in a river while looking for Pokémon. A civilian (ie, not a player) discovered that the old church in which he lives had been tagged by Niantic, the firm that developed the game, as a “gym”—a meeting-point for players wanting to do battle, dozens of whom had duly begun arriving outside his house. Most gyms seem to be in public places, suggesting the man’s home was tagged by mistake, though there is, at present, no way to have the tagging undone.

Much like Pokémon, pundits are now engaged in a virtual battle over what the game’s success means. Is it just a fad? Possibly. Will it help augmented reality go mainstream? Probably. How much money will Nintendo make with “Pokémon Go”? Although the app itself is free, players buy virtual items to strengthen their Pokémon. That “freemium” model has earned riches for other firms. And Niantic wants retailers and other firms to sponsor locations in its virtual world. In any case, Nintendo’s owners should be happy: the firm’s shares are up by over 50% since the game’s release, adding $11 billion to its valuation.