Have you noticed a distinct uptick in the number of people on your commute who appear completely engrossed in their phones? Grown men and women who have stopped, perhaps, right in the middle of the sidewalk, oblivious to the world around them? No? 

That's probably because you, too, are hopelessly addicted to Pokémon GO.

Pokémon - the venerable Nintendo franchise that's been around for twenty years, if you can believe it - has made the jump to mobile devices, and the response has been extraordinary. The new game, which uses augmented reality to overlay the world of Pokémon on top of a simplified Google Map, instantly became the most-downloaded app in the iOS app store, and currently has as many daily active users as Twitter. Nintendo's valuation has jumped by $7.5 billion on news of the app's positive reception. 

What we find most interesting about GO, though, is its popularity among older users. In our own unscientific observations - and those of a handful of blogs also reporting on the phenomenon - a large number of Pokémon GO players appear to be millennials, the same generation that played the original game on their Game Boy handhelds. They may have aged out of the original target, but they've shown no qualms about jumping back into a childhood obsession on their smartphones.

Ultimately, Pokémon's success is in its core formula - a finely-tuned system of challenge, reward and item-collecting that has proven highly addictive. And facing a grown-up user base equipped with mobile devices, Nintendo has been able to adapt their franchise's core mechanics to the kind of bite-size play that has driven success for other mobile games.

We fully admit that we don't know whether GO will keep growing; plenty of apps have seen explosive adoption early on, only to fizzle. Even Nintendo's own first app, Miitomo, saw its substantial hype melt away as users tired of the game's basic premise. 

But here's what we do know:

- Pokémon GO represents a massive success for Augmented Reality. We've been talking about AR for years, but the technology has always struggled to find a mass audience. This may, finally, be its watershed moment.

- Millennials' nostalgia for the 90s of their youth is a powerful force. They're proud of their geeky pasts, and not above revisiting them. A youth spent playing video games and collecting trading cards is a badge of honor.

- Pokémon GO is escapism, and in a world that feels increasingly chaotic, immersive fantasies hold particular sway. In the words of Gizmodo's Matt Novak, this is the photo of the summer: