Crowds stampeded after a Vaporeon in Central Park and people fell off cliffs playing it in California.
At an Apple event on September 7, Niantic CEO John Hanke said 500 million people had downloaded the game in just two months.
It was the first mobile game to go mainstream in a big way since "Candy Crush" in 2014 or "Angry Birds" in 2012. It was also the first to incorporate augmented reality, a blending of the real and virtual worlds.
Twitter mentions of the game peaked at 1.7 million on July 11, five days after its launch, according to Adobe Digital Insights. That number had fallen by 98 per cent, to 131,000, by September 7, when Apple featured it.
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Was it all a summer fever dream? While experts say the game is likely to remain popular for a while, it needs to evolve to have real staying power - just like its namesake digital creatures.
Of course, an enormous number of people still play the game. Research firm App Annie estimates 1 in 10 smartphone owners in the US are playing; in Japan, that number is 1 in 4.
Those US figures are half what App Annie saw the week after the game launched, but to put them in perspective, they still reflect roughly the same user interest as Twitter or Pinterest.
"Pokemon Go" has also been good at keeping people playing after signing up. Its 30-day retention rate is the second best on the Google Play store behind "Words with Friends," but ahead of other popular games such as "Clash of Clans" and "Clash Royale."
"Right now, yes, they're losing a million players every week. But they get a million new players every week."
The longer users interact with the game, the more time a company has to figure out how to get money from them, Nicolas said.