"LOST. The Cube," read the ad, posted at the top of the paper's "Notices" section. "Reward Offered. Not only an object of great significance to the city but also a technological wonder."
The cryptic notice, along with several subsequent ads in The New York Sun, The Times of London and Monday's Sydney Daily Telegraph, are the first tangible signs of a mystery called "Perplex City" beginning to unfold online.
It 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.