When you log in to Shadow Cities, you see your actual location, as if you were using a satellite map program, which you are (using the iPhone’s GPS service). If you are in a reasonably populated area, you will also see nearby “gateways,” based on local landmarks. You then take control of those gateways and use them to power additional structures that allow you to grow in strength and stake a claim to control of your ’hood. When you log off, your empire remains, until some enemy players come along and raze it.

Image Shadow Cities This iPhone battle game lets players compete in real time and in real places. Credit... Grey Area

Of course you’re not alone. Right there on the screen you will see other nearby players in real time, and not all will be friendly. When you start the game, you must choose between two factions, the Animators (nature lovers) and the Architects (technologists). These cabals are locked in an eternal struggle, and at any time you can zoom out and survey the surrounding area for miles to determine which side is winning around you. More broadly, the game is structured in a series of weeklong campaigns, with separate scoreboards for various countries and states.

But why stay home when you have an entire planet to explore? The most far-reaching (literally!) aspect of Shadow Cities is that you can set up a beacon at your location for other players to visit from anywhere in the world. So you may be tending your little fiefdom in, say, Paramus, N.J., when you read an alert from another player that a big battle is brewing in, say, Paris. You jump to a friendly beacon and the next thing you know, you’re lobbing spells against enemy players from all over the world for control of the Champs-Élysées. Or you’re in Rome battling for control of the Vatican, or in Washington sniping over the Ellipse.

In the last week I have projected my consciousness through Shadow Cities to locations ranging from Poughkeepsie, N.Y., to Plaucheville, La. I’ve explored Cannes, France; Helsinki, Finland; London; Vienna; and San Francisco. I’ve visited friendly bases all over the Midwest, not to mention Turin, Italy; Honolulu; and Bridgeport, Conn.

Riding through Manhattan the other day, I asked my friend to pull over so I could demolish an enemy base on East 71st Street. Landing in Atlanta this week, I logged in to Shadow Cities, made common cause with a fellow Architect and set up a temporary base at the airport for our layovers. Woe betide the opposing Animators who got off their planes!