Every few feet, I spot one. Or rather, I spot a gaggle, as they often travel in small groups. At first, you might dismiss them as any other person too obsessed with their phones, heads and shoulders stooped, eyes staring intently at that 4-inch screen. Their hands give it away though. They often hover their index fingers over the screen, flicking every once in a while, like they’re playing digital shuffleboard, and their finger’s the cue.

That, and they’re often heard muttering things like, “I almost had him!” or “Another friggin’ Weedle?! Nobody wants another Weedle!” Or, as the ultimate tell, they’re humming “Gotta Catch ‘Em All.”

Pokemon Go players have taken over New York City faster than the “Harlem Shake” in 2012, and it’s showing no signs of stopping. And I’m perfectly okay with that.

The free app uses your phone’s GPS to show Pokemon hidden all around you. When you walk around with the app open on your cell, you’ll see a map of your surroundings, and every so often, a Pokemon will pop up on screen. When it does, you’ll have the option of throwing pokeballs to try to catch it (hence the tell-tale finger-swiping motion most players have when they walk down the street). The app uses your camera to make it look like Pokemon are popping up all around you, in real life. You can even take a picture of the Pokemon you see, and share it on social, which you may have noticed, oh, 32 of your closest acquaintances do this weekend.

After a few levels, you can search for “gyms” in the area to fight your Pokemon, proving you’re the very best, like no one ever was.

It’s amazing to see the app’s meteoric rise over the past week — within two days of going live, every 1 in 20 phones had downloaded it, according to Fortune — especially since, at its core, it’s a virtual reality version of Geocaching, the game where little logs and trinkets are hidden in plain sight. Pokemon Go takes things to the next level, making it easier than ever to find and collect “trinkets” (in this case, Pokemon), share them with friends and spread the word. Plus, it’s built on nostalgia, given it a built-in audience eager to check it out.

It was nostalgia that drove me to download it. Jokingly, I created an avatar with friends. And while I haven’t felt compelled to play it all day, every day, I’ll be honest: It is pretty addictive, in the way that you might scroll Instagram when you’re waiting in line, or peruse Facebook when you need to defrag your brain after a long day.

While there are some very valid concerns about the game (teens were recently robbed after following a ‘beacon’ someone set up in the game; some say they were injured while walking and playing), it’s worth checking out, especially if you’ve ever Geocached. Or spent the late ’90s with a Gameboy in your back pocket.