The magic of "Pokemon Go" is in the way it overlays the Pokemon world atop the real world. Step outside and you'll spot cartoonish creatures to capture. Head to a place where people congregate - say a park or a bus stop - and you'll battle other players or encounter the rarest beasts.
In the two weeks since the app's launch, random locations have essentially become arcades for the mobile gaming set - attracting crowds of phone-toting players at all hours.
That's a problem for the University of California at Irvine Medical Center, which is the unenthusiastic host of five Pokemon hubs - dubbed gyms and Pokestops - across its campus.
"What we're trying to do is discourage people who don't have a legitimate reason to be at the hospital (from coming) here looking for Pokemon," hospital spokesman John Murray said.
The hospital wants out of the app - and it's not alone. Arlington National Cemetery outside Washington, D.C., the National September 11 Memorial and Museum in New York City and the Auschwitz-Birkenau State Museum in Poland have asked visitors to stop playing out of respect. Funeral homes sought an exclusion from the game as the blog Pokemon at Funerals shared images of people playing at services.
Such conflicts have raised pressing questions about games and other products that blend the real world and the digital world using a technology called augmented reality.
Exactly how much of reality should be augmented?
"When people are being directed by the gameplay to enter inappropriate or dangerous places, there are a whole host of different questions that need to be addressed whether or not the gameplay is to blame," said Darren Cahr, an intellectual property attorney in Chicago. "No one really knows how far people are going to push this."
Many in the gaming industry doubt it was the intention of Niantic Labs, which developed the game, to create uncomfortable situations at memorials or distractions for staff at hospitals.
The app usually designates geographic landmarks big and small as Pokestops and gyms. It knows the location of those sites based on data from Niantic's first augmented reality game, Ingress.
Ingress isn't known for causing real-world problems or for its big audience. Analysts say the 3-year-old game has 1 million monthly users - a fraction of the 15 million Pokemon has racked up in just days.
With such a difference in scale, there's no way Niantic could have seen this coming, said Sunny Dhillon, a partner at Signia Venture Partners, a fund that invests in games involving augmented reality.
"I'm willing to give the game developer the benefit of the doubt," said Dhillon, who predicts engineers will tinker with the game to help reduce these real-world faux pas. "A lot of the privacy issues were unanticipated."
Niantic launched the app without giving locations the ability to opt out. That hasn't stopped many establishments, including UC Irvine Medical Center, from contacting the company asking to be left out. (UC Irvine Medical Center says it has not heard back from Niantic, and Niantic declined to comment for this story).
Some tech experts predict Niantic will create a feature that allows establishments to opt out (though that could raise its own questions: Which requests coming from affected establishments are valid?)
But because of the game's huge success, some question whether those changes will come soon.
Now that "Pokemon Go" is, by some estimates, the biggest-ever mobile game in the U.S., the San Francisco company has lots on its plate. Since its launch, there have been complaints about bugs and faulty servers that will probably take priority. Then there's building the business side of the game with in-app purchases and advertising.
Julia Ask, a media analyst at Forrester Inc., says it's not Niantic's place to tell people how to behave.
She compared the situation with kids eating dinner with their phones out. Some parents would ask them to put them away during the meal; others wouldn't care.
"It's an old-fashioned value," she said. "It's more of a point of view of how people should experience their space. It's a public space, and they can't enforce that."
Both Ask and Cahr said businesses that don't wish to participate in the game should put up signs asking users not to play.
Murray, of UC Irvine Medical Center, said the hospital is "developing some messages" to discourage gamers from entering the facility. But, he said, turning away gamers shouldn't be the hospital's responsibility.
Boosters of augmented reality predict more apps to use the technology in the coming years. The success of "Pokemon Go" suggests they'll have a captive audience - and the potential for real-world friction.
"Its just the beginning," Cahr said. "Five years from now, 10 years from now, people are going to look back at this as quaint and will be amazed at far these things have really gone."
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