The US is Pokémon GOing

Pokemon GO players around Manhattan.

"I just played for half an hour in Times Square, and I've already collected four rare Pokémon. It's more than the number I could get walking around nonstop in Long Island for half a day," she said. "I got too many Rattatas (rat-like Pokémon) and Pidgets (bird-like Pokémon) in Long Island. I've captured 120 Pidgets in four days since I started playing."

As a virtual reality (VR) game designer with six years' professional experience, Garrahan, however, said the difference is unlikely the result of an intentional design.

"They might have designed a complicated program with a higher level code to randomly place the Pokémons and Pokéstop in different places. But as they are not doing it by hand, there's absolutely no geographical discrimination in the designing process," he said.

Others complain that the Pokémon GO server crashes too often when it is overloaded with players.

Paul Michael, 26, a Pokémon trainer since the game was introduced, said he felt frustrated after spending "centuries" waiting for the server to restart.

"I almost caught a Aerodactyl (a rare dragon-like Pokémon) half an hour ago, but the server went down. I hated my life a little bit when it happened," he said, while trying to repeatedly reload the game.

It's not the first time the game's design has been criticized as faulty. Shortly after its release on July 7, Pokémon GO was reported to be seeking full access to a user's Google account, which raised concerns about privacy. The developers acknowledged the flaw on July 12, five days after the game's release, and issued updates to ensure users' information was protected.

Other safety concerns arose when the game went beyond the internet. Some people worried that players become less aware of their surroundings when they are immersed in the half-fantasy world the game creates.

"Many players are like zombies in the streets", said Sandra Chen, 30, a Pokémon player in New York City. "They keep their heads down, staring at the screen in case a Pokémon pops up."

Kyrie Tompkins, a Maine web designer, twisted her ankle trying to catch a Pokémon.

"My ankle still hurts and I missed the Jigglypuff (a small pink Pokémon)," she wrote in a tweet on July 7.

Reddit user "Amalthea" said that "Pokémon GO put me in the ER (emergency room)" on July 7.

"Not even 30 minutes after the release last night, I slipped and fell down a ditch. Fractured the fifth metatarsal bone in my foot, six to eight weeks for recovery," said "Amalthea".

A security guard at Microsoft, who refused to provide his name, said that the company's Manhattan office has closed one of its building's doors to stop Pokémon players from gathering in the lobby, because a "Gym", a place for Pokémon trainers to battle, is right across the street.

A police station in San Francisco issued Pokémon GO safety tips to remind players of potential dangers, asking players to obey traffic laws, avoid running into obstacles and stop riding bikes or skateboards while playing the game. The New York City subway authority sent a tweet on July 11 alerting players to not get close to train tracks when playing Pokémon GO in subway stations.

Interviews in Times Square with Pokémon GO players revealed that they haven't encountered any safety issues, and they said that they stay alert while playing.

"It says in the beginning of the game, 'stay aware of your surroundings'," said Reyes. "I always tell myself the road is not where the Pokémons are going to appear. They are going to be right down the sidewalk, so I either catch them before going across the road, or wait until I get across first."

Despite the drawbacks, Pokémon GO players and the game's developers are positive about its future and also the AR game market.

"This is the most popular AR game that ever existed. We are definitely going to see a lot of clones," said Garrahan.

Judy Zhu and Nancy Kong in New York contributed to this story.