Elsa Jenna

Alternate reality games existed before the iPhone, using email, fake ads, and even faxes to send players on clue hunts. But thanks to the smartphone, games now include geospatial triggers and social media integration, allowing players to seamlessly interact with one another and the world around them.

Even Google has gotten involved, through its in-house startup Niantic Labs. Helmed by founder John Hanke, the group released an ARG called Ingress in 2012. (Two factions fight to control an alien substance; players tag locations with their phones to vie for control of the “portals” that spew it.)

Up next for Niantic: Endgame, a project with Oprah-antagonist James Frey that will incorporate an ARG with a million-dollar gold-bullion prize. Hanke was tight-lipped on details, but he was happy to share his favorite ARGs to bedevil us in the meantime.

CICADA 3301, UNKNOWN

This puzzle conceals clues inside of images, QR codes, and the secretive Tor network, among other places. “There are hardcore crypto people trying to break it,” Hanke says. (Follow along at uncovering-cicada.wikia.com.) Hanke has heard rumors that a government agency created it as a recruitment tool.

BLACKHOLLOW PROJECT, BY IMMERSIVE FICTION

Players cooperated to unravel a series of interlaced stories about time travel and World War II. Retrace their steps at blackhollowproject.com.

THE WALK, BY SIX TO START AND NAOMI ALDERMAN

People run or walk to trigger a story line about an electromagnetic pulse attack on the United Kingdom (stateside Anglophiles can also download the app to play). As players accumulate footfalls, they receive items and unlock audioclips.