A ringing cake. Sure, it reads like a lost lyric from "MacArthur Park," but it's actually a key moment in the history of media, marketing and perhaps even marzipan.

As recounted by Wired Magazine contributing editor Frank Rose in his recently released tome, The Art of Immersion: How the Digital Generation Is Remaking Hollywood, Madison Avenue, and the Way We Tell Stories, the cake was part of an alternative reality game qua marketing campaign to promote the last Batman flick The Dark Knight, featuring Heath Ledger as the Joker. How a Boston couple found themselves in a bakery asking for a package that contained the cake (and a phone number scrawled upon it in icing) is too elaborate to relay, but suffice it to say, they and hundreds of thousands of other participants, online and elsewhere, were enthralled.

When the couple dialed the number, a mobile phone that had been stashed inside the cake began to ring. Such was the fiendish genius of the game architects at Pasadena-based 42 Entertainment, and precisely the kind of touch the Joker himself might employ. Instructions followed, and the couple and several others who'd enjoyed similar interactions with the game eventually went on to a private teaser screening. Throughout, a legion of fans followed and aided the unlocking of various clues online, which drew them further into the narrative of not only the game but the Batman flick as well.

Participatory campaigns, though not yet par for the course, are frequently being baked in (as it were) to extend narrative experiences beyond our screens and into our daily lives. Throughout his book, Rose examines dozens of such immersive entertainments and makes a compelling case that the best way to enjoy a story is perhaps from within.

The inadvertent Zen notwithstanding (mine, not Rose's), one way to reach an audience and have them truly internalize a story (and perhaps develop an addictive need to pony up for its various permutations) is to have it intrude on their external reality. Or their toilet stall—after all, that's what Nine Inch Nails brain trust Trent Reznor did to promote his mid-aughts album Year Zero. A USB drive containing information germane to a post-apocalyptic puzzle that expounded upon the album's themes was left in a venue's restroom during a live concert. A young woman discovered the drive and realized it contained an unreleased track, which she uploaded to the web where it went viral. Moreover, the metadata of the track itself was strewn with clues to Reznor's cryptic vision.

At first blanche, the notion of tracking all the curios and red herrings embedded in these projects might seem exhausting, or perhaps only the province of those with OCD. To a rabid fan, however, it's a portal to a parallel universe wherein they can revel in the creation of their favorite artists, characters and stories. Prior to this shift to transmedia-driven engagement, fan fiction (the unsanctioned continuation of narratives by die-hards) was where acolytes and authors shared an uneasy pas de deux. Now, some content creators prefigure the audience's desire to be "in-world" in their earliest conceptions.

Like a vampire, however, this can only be achieved through invitation. Fans willingly subsume themselves into the narrative and its myriad points of interactivity (which, increasingly, unfold in a nonlinear manner) such that they essentially become co-authors of the story, motoring it along from rabbit hole to rabbit hole, uncovering clues and delivering their revelations to their online brethren.

"Stories become games; games become stories," writes Rose. What's fundamental and a likely motivator for much of the activity that swarms around a TV series like Lost, video games like Halo and pretty much anything under the banner "anime," is a propensity not just to actively indulge in a fictional universe but to indulge in it with others. As Rose later explains, "Stripped of the apparatus of advanced civilization and pecuniary gain—stripped of Hollywood and television and publishing—storytelling is a simple act of sharing."

So don't be surprised when someone invites you to share some confectionary creative content with them—like perhaps a slice of ringing cake.

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