“Perplex City” is the latest well-funded entry in a young medium called “alternate-reality gaming”–an obsession-inspiring genre that blends real-life treasure hunting, interactive storytelling, video games and online community and may, incidentally, be one of the most powerful guerrilla marketing mechanisms ever invented.

These games are intensely complicated series of puzzles involving coded Web sites, real-world clues like the newspaper advertisements, phone calls in the middle of the night from game characters and more. That blend of real-world activities and a dramatic storyline has proven irresistible to many.

“It’s a very addictive form of entertainment,” said Steve Peters, a Las Vegas musician who is one of the founders of the Alternate Reality Gaming Network, a set of Web sites devoted to the topic. “People stay up all night; it really is very immersive.”

It’s exactly that dedication that has made alternate-reality games powerful marketing mechanisms. The two biggest games so far have been associated with products: Stephen Spielberg’s “A.I.” movie and Microsoft’s “Halo 2.” Advertising executives say it’s a promising tool.

“When other people are missionaries for your brand, you’ve got something special,” said Jordan Fisher, director of brand planning at Perceive, an advertising agency in Los Angeles. “The brand becomes something much bigger, has a purpose rather than being just another product on the shelf.”

To many players, that marketing role barely matters, however. If the experience in an alternate-reality game, or ARG, is good, that’s all that matters, they say.

“If done by the right people, ARGs of any style can be amazing things,” said Geoffrey May, a player from Canada. “Whether it’s selling something or it’s just for fun, most ARGers simply enjoy the game itself.”

More here.