The massively popular smartphone game "Pokemon Go" is raking in huge profits for parent company Nintendo, even as some raise privacy concerns over how closely players' movements are being followed in the GPS-enabled game.

Nintendo shares have spiked 12.7 per cent since the game was released in select countries last week, boosting profits by billions of dollars in a matter of days. The game is one of the most popular apps on Android and Apple iOS devices, with more daily users than Tinder, according to reports. And the game still hasn't been released in some countries, including Canada.

In the game, players are encouraged to wander the real world in search of virtual monsters, which are visible through the smartphone camera and positioned using GPS. The game tracks the distance users walk, and encourages players to visit physical locations to gain power-ups and battle other Pokemon.

Tech journalist Andy Walker attributes the game's success to the nostalgia factor of the Pokemon brand, which was first introduced in 1995. "There's a lot of adults jumping on this because they used to play a version of this as a kid," he told CTV News Channel on Tuesday. "A lot of the people that are playing it now were kids at the time, collecting the Pokemon cards and playing the Nintendo Pokemon video games."

He added that the real-world aspect of the game is "ingenious," and is likely to inspire many more GPS-based games in the future. "This is the beginning," he said.

Security concerns

However, some are already accusing the game's developer, Niantic, and Google Maps of siphoning user data from the app to track people's movements.

In a statement to Mashable on Monday, Niantic acknowledged that "Pokemon Go" was "erroneously" requesting full access to users' Google profile information, when it only needs basic info (i.e. the user's ID and email address).

"No other Google account information is being accessed or collected," the company told Mashable. Niantic says it has confirmed with Google that no other info has been accessed, and it is now working on a "client-side fix" to address the situation.

"Google will soon reduce Pokemon Go's permission to only basic profile data that Pokemon Go needs, and users do not need to take any actions themselves," the company said.

Security experts say it's extremely rare for an app to require full access to your Google account. Apple's iOS, for instance, asks for access to your email, calendar, contacts and basic account info, but does require full access to know what you're doing, where you're going and who you're speaking to.

"When you grant full account access, the application can see and modify nearly all information in your Google Account," Google says on its support page.

Security expert Adam Reeve says granting an app full access allows it to read and send emails, review your search history, access your Google Drive documents, look up your Maps navigation history and access any private images in your Google Photos account.

Reeve acknowledges in a later post that Niantic and Google are working on addressing the issue. "I'm really happy they're addressing the issue promptly," Reeeve wrote. "Now everyone go catch some Pokemon."

Real-world hijinks

While the game's security issues are on the road to being addressed, some of its real-world implications are only now being revealed.

In Missouri, for instance, four men were arrested for allegedly luring "Pokemon Go" users to a Pokemon hotspot, using an in-game power up that makes it easier to find monsters there. "Apparently they were using the app to locate people standing around in the middle of a parking lot of whatever other location they were in," the O'Fallon Missouri Police Department wrote in a statement on their Facebook page.  And earlier in the week, a a woman in Wyoming discovered a real dead body while she was hunting virtual Squirtles by a river.

However, the game is also being hailed for its fitness and social aspects. In addition to its requirement that players walk around to find Pokemon, the game also encourages users to visit real-world sites that are labelled as gyms and "Pokestops" in the virtual world.

A Massachusetts man says he's had a steady stream of "Pokemon Go" users stopping in front of his house in recent days, because it has been designated a virtual gym in the game.

"I actually live in an old church," Boon Sheridan, of Holyoke, Mass., told CTV News Channel. He said the building was converted to a residence in the 1970s, "but it's in the 'Pokemon Go' database as a church, and most churches in the database are listed as gyms."

Sheridan says he was initially confused to see so many people stopping in front of his home, either on foot or in their cars, to battle at the gym. However, once he learned what was happening, he says he spent some time outside so he could meet the visitors. He says more than 50 people dropped by on Saturday, at a rate of two or three people an hour.

"It was great because it turns out a bunch of them are my neighbours," he said. "It started out a little awkward, but it's turned into something that's been a little easier to deal with."

He added that most visitors stay on the sidewalk or stand in the park across the street, and none of them have come inside the wrought iron gate surrounding his property.

"It's hard to be too angry about," he said.

The New York City Subway recently tweeted a warning to "Pokemon Go" players, instructing them to keep their distance from the tracks while chasing the virtual monsters.

"Pokemon Go" monsters pop up near various locations in the real world, but players don't actually have to chase them once they appear in the game.

Businesses catching Pokemon players

A handful of business owners have already figured out how to capitalize on the "Pokemon Go" craze by exploiting Pokestops near their stores. In Atlanta, an advertising agency spent $40 of real-world money to buy in-game lures, which can be placed to attract rare Pokemon to a check-in spot on the map. The agency placed the lures at two Pokestops near its company-run café, and reported a surge in business from Pokemon-chasing visitors to the area.

"Our corner was essentially lit up all day long," Derek Fridman, the executive creative director of Huge, told The Associated Press.

A deli in San Francisco employed a similar tactic, setting up lures at two nearby Pokestops and advertising itself as a charging station for the battery-intensive app. Owner David Nottage III said players "have no choice but to walk past us," so it made sense to capitalize on the situation.

With files from The Associated Press