Alternate realty gaming: a combination of puzzles, real world exploration, scavenger hunts, and on-line searches.
Harajuku Fun Madness is the best game ever made. I know I already said that, but it bears repeating. It's ARGing, Alternate Reality Gaming, and the story goes that a gang of Japanese fashion-teens discovered a miraculous healing gem at the temple in Harajuku, which is basically where cool Japanese teenagers invented every major subculture for the past ten years. - from Little Brother by Corey Doctorow