I’m not usually very political, but I recently joined the Resistance, fighting to protect the world against the encroachment of a strange, newly discovered form of energy. Just this week, in fact, I spent hours protecting Resistance territory and attacking the enemy.

Don’t worry, this is just the gloomy sci-fi world depicted in a new smartphone game called Ingress created by Google. Ingress is far from your normal gaming app, though—it takes place, to some degree, in the real world; aspects of the game are revealed only as you reach different real-world locations.

Ingress’s world is one in which the discovery of so-called “exotic matter” has split the population into two groups: the Enlightened, who want to learn how to harness the power of this energy, and the Resistance, who, well, resist this change. Players pick a side, and then walk around their city, collecting exotic matter to keep scanners charged and taking control of exotic-matter-exuding portals in order to capture more land for their team.

I found the game, which is currently available only to Android smartphone users who have received an invitation to play, surprisingly addictive—especially considering my usual apathy for gaming.

What’s most interesting about Ingress, though, is what it suggests about Google’s future plans, which seem to revolve around finding new ways to extend its reach from the browser on your laptop to the devices you carry with you at all times. The goal makes plenty of sense when you consider that traditional online advertising—Google’s bread and butter—could eventually be eclipsed by mobile, location-based advertising.

Ingress was created by a group within Google called Niantic Labs—the same team behind another location-based app released recently (see “Should You Go on Google’s Field Trip?”).

Google is surely gathering a treasure trove of information about where we’re going and what we’re doing while we play Ingress. It must also see the game as a way to explore possible applications for Project Glass, the augmented-reality glasses-based computer that the company will start sending out to developers next year. Ingress doesn’t require a head-mounted display; it uses your smartphone’s display to show a map view rather than a realistic view of your surroundings. Still, it is addictive, and is likely to get many more folks interested in location-based augmented reality, or at least in augmented-reality games.

Despite its futuristic focus, Ingress sports a sort of pseudo-retro look, with a darkly hued map that dominates the screen and a simple pulsing blue triangle that indicates your position. I could only see several blocks in any direction, which meant I had to walk around and explore in order to advance in the game.

For a while, I didn’t know what I was doing, and it didn’t help that Ingress doesn’t include any street names. New users complete a series of training exercises, learning the basics of the game, which include capturing a portal, hacking a portal to snag items like resonators (which control said portals), creating links of exotic matter between portals to build a triangular control field that enhances the safety of team members in the area, and firing an XMP (a “non-polarized energy field weapon,” according to the glossary) at an enemy-controlled portal.

Confused much? I sure was.

But I forged ahead, though, hoping that if I kept playing it would make more sense. I started wandering around looking for portals. Portals are found in public places—in San Francisco, where I was playing, this includes city landmarks such as museums, statues, and murals. Resistance portals are blue, Enlightened ones are green, and there are also some gray ones out there that remain unclaimed.

I found a link to a larger map of the Ingress world that I could access through my smartphone browser and made a list of the best-looking nearby targets. Perhaps this much planning goes against the exploratory spirit of the game, but it made Ingress a lot less confusing for me (there’s also a website that doles out clues about the game and its mythology).

Once I had a plan, I set out toward the portals on my list, all of which were in the Soma and Downtown neighborhoods of San Francisco. I managed to capture two new portals at Yerba Buena Gardens—one at a statue of Martin Luther King, Jr. and another at the top of a waterfall—and link them together.

Across the street, in front of the Contemporary Jewish Museum, I hacked an Enlightened portal and fired an XMP at it, weakening its resonators. I was then promptly attacked. I fled, figuring I wouldn’t be able to take down the portal by myself.

A few hours later, much of my progress was undone by a member of Enlightened (Ingress helpfully sends e-mail notifications about such things). I was surprised by how much this pissed me off—I wanted to get those portals back for the Resistance, but pouring rain and the late hour stopped me.

Playing Ingress was a lot more fun than I expected, and from the excited chatter in the game’s built-in chat room, it was clear I wasn’t the only one getting into it.

On my way back from a meeting, I couldn’t help but keep an eye out for portals, ducking into an alley to attack one near my office. Later, I found myself poring over the larger map on my office computer, looking at the spread of portals and control fields around the Bay Area.

As it turns out, my parents live in an area dominated by the Enlightened. So I guess I’ll be busy attacking enemy portals in my hometown this weekend.