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Ask your squirrely colleague in the next cube what he's been doing lately. If he responds, "I'm part of the Joker's army,'' don't be alarmed. Chances are, he's one of the apparently millions of adults already immersed in an alternate reality game (ARG) 15 months in the making, and now playing out in real time worldwide in collective (and perhaps breathless) anticipation of the July 18 release of the Batman movie, The Dark Knight.

The whole thing started when people in comic book stores (natch) found Joker cards stamped "I believe in Harvey Dent,'' which led them to IbelieveinHarveyDent.com, which set up three threads, which allowed users to find clues and begin experiencing life in a digital Gotham City. Whew.

I am what Gawker.com would term "an old,'' so even though I have a soft spot for comic book geeks, I really wouldn't choose to spend time on a puzzle site that, when fed the right clues, changes individual pixels on the image of Harvey Dent so that it eventually reveals a picture of the latest Joker. (He, sadly, is played in the movie by Heath Ledger. Just reading about how Ledger isolated himself for a month to live his interpretation of the part of a modern day sociopath is tough.)

But back to the game. Even if I don't want to play, I can appreciate the genius behind telling stories across multiple platforms while building this subversive yet coherent alterna-universe. It's the work of the company 42 Entertainment, made up of incredible engineers, programmers and even some former Disney Imagineers. And since, as you read this, the Dark Knight game is still playing out around the world, the company won't reveal much.

But what is up for review is 42's work on the ARG for Year Zero, the Nine Inch Nails concept album of 2007. The game just won the Cyber Grand Prix at Cannes.

It is a work of virtuosity that played out over 10 weeks and engaged more than 2.5 million participants -- and was the third-most searched term on Yahoo!. (Who knew?)

It turns out that Trent Reznor, Nine Inch Nails' forward-thinking frontman, e-mailed the general 42 Entertainment Web site after getting involved in one of its earliest projects, "I Love Bees,'' for the launch of Halo 2.

A guy who's been quoted as saying he hates the word "marketing,'' Reznor long ago gave up on the antiquated idea of recording labels distributing CDs to music stores and started experimenting with alternate delivery systems, for both music and entertainment.

He sees this ARG not as some sort of "sales gimmick,'' but as a "continuation of the art of the recording. It is the art form.''

This group dynamic fits right into the definition of post-Post Modern art, the idea that unless someone watches the artist or a group creating the work, it doesn't exist, and that watching or participating changes the art.

Reznor is actually way ahead of himself in having his fans do online remixes of his music. The album's first single, "Survivalism," and other tracks from Year Zero were released as multitrack audio files for fans to remix from the Web.

Set in 2022, the story line mixes several elements, including dystopian themes from Ray Bradbury's Fahrenheit 451 (censorship) and George Orwell's 1984 (government surveillance). Although I'm not much for imagining "a dark future of endless Holy War and environmental collapse," many people want to become a part of this world, through a game that's part online scavenger hunt and part hippie be-in, tied together under the slightly pretentious banner phrase "Art is resistance."

It started on Feb. 12, 2007, with a Nine Inch Nails tour T-shirt that contained highlighted letters that spelled out the words "I am trying to believe," which in turn was registered as a Web site. Before Year Zero's release, songs from the album were reportedly found on USB drives hidden at NIN concert venues -- specifically behind the toilets in the bathrooms. The physical CD also was filled with clues, including a phone number for the game's Department of Morality.

Some of the U.S. participants who submitted their own artwork with that battle cry were selected to meet at a corner in Los Angeles. There they were relieved of their cell phones and personal property and taken by van to an undisclosed location, where they took part in a live concert with the band.

However you explain it, and whatever you want to call it, it's pioneering art. At the same time, if the point of it all is to get people to think about social change and speak up, it is downright sad to have all that energy radiating in a fake universe.