LOS ANGELES -- As throngs of "Pokemon Go" players traipse around to real-world landmarks in pursuit of digital monsters, some ticked-off property owners are asking to have their locations in the fictional Poke-verse removed.

For Valerie Janovic, a 19-year-old psychology major at Brandeis University, the game went too far when the image of a poison-gas-emitting pocket monster called "Koffing" was pictured near the U.S. Holocaust museum's exhibit on World War II gas chamber victims. Her online petition to have the site removed from the game has collected more than 4,500 supporters by Thursday.

"I just don't think people should be playing a game where people remember people who suffered and were tortured and who died," she says.

Besides the U.S. Holocaust Memorial Museum in Washington, several churches and cemeteries including Arlington National Cemetery want their in-game locations removed to keep crowds of players away.

The addictive, location-aware smartphone game gives digital incentives like "Pokeballs" as rewards for visiting real places. The locations, known as "Pokestops" and "Gyms," are based on landmarks submitted by players of Niantic's earlier game, "Ingress."

Niantic offers a form to request exclusion, but it's neither automatic nor guaranteed. It's a mystery how quickly, if at all, Niantic will respond. Several requesters said they got a stock response saying, "Thank you for reporting this PokeStop/Gym. We will review and take appropriate action."

At first, web designer Boon Sheridan was just mildly annoyed at the traffic and cars that blocked the driveway to an old church that has become his home in Holyoke, Massachusetts. It was labeled a "Gym" where players pit their Pokemon, or pocket monsters, against each other in battle. His attitude changed when his virtually obsessed visitors began leaving behind physical trash.

"There's a lovely public park across the street so we've suggested (the developers) adjust the GPS co-ordinates," he said.

At the East Renton Community Church in Renton, Washington, players have come by day and night, sometimes leaving the gates open, a potential invitation to criminal activity, office manager Rona Heenk said.

"We can't possibly monitor it all the time, and we don't have a way to discern whether or not the adults who are coming to play the game are just here to play or 'casing' our location," Heenk said.

Mobile Memorial Gardens, a cemetery in Mobile, Alabama, had a dozen gamers show up Wednesday, some walking around burial plots with cellphones in hand, others driving aimlessly down roads. President Timothy Claiborne said he's all for people having fun, but would prefer they have it at a local park.

"This is private," he said. "I owe it to the families we serve to provide a sense of decorum here."

Ryan Calo, a University of Washington law professor, said private property owners may adopt a "Pokemon No Go" policy and bar players from physically entering their building or grounds. But he said there's no legal right to compel the game's creators to remove a location from its lines of code.

"It's important to note that the Pokemon are not there on the property," he said. "What's happening is that a particular location triggers the display of a digital monster on your phone. The monster is only on your phone."

Niantic, which has Japanese game company Nintendo as a major investor, didn't respond to requests for comment.

To be sure, gaining designation in the game as a "Pokestop" or "Gym" can be beneficial. Cafe owners have set up in-game lures to attract unique digital creatures in the hopes potential patrons with real money chase them into the store. The Adventure Park playground in a forested part of Maryland invited "Pokemon Go" players to come to take advantage of its lures this weekend and get $5 off admission.

Niantic CEO John Hanke told The Financial Times that the company was sell sponsored locations in the game, much like it did with its previous game.

Clever coders like Manmeet Gill, a 13-year-old high school student in Sydney, Australia, even found evidence in the "Pokemon Go" app code that burger giant McDonald's may be preparing to sponsor locations in the game. Included in the code is text that reads "Sponsor.Mcdonalds.POKEMON--STORE" and a logo of its double arches. Although McDonald's spokeswoman Lisa McComb said she didn't have any news to share, Gill said it was "highly unlikely" such code was there by accident.

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AP Technology Writers Brandon Bailey in San Francisco and Barbara Ortutay in New York contributed to this report. Anderson reported from New York.