Alternate Reality Game
From LGPedia
Some fans initially suspected that lonelygirl15 was an Alternate Reality Game, a type of game that overlaps the game world with reality, by utilizing real world media, such as YouTube, phone calls, or blogs, to deliver an interactive media experience with players. The people who run an ARG are often referred to as "puppet masters".
Once lonelygirl15 became an internet phenomenon, several ARGs were developed around the lonelygirl15 storyline. The largest of these games, Cassieiswatching, became a phenomenon in its own right.
The Homeschoolers Aggregate, Facility J and OpAphid could also be considered alternate reality games. OpAphid was later endorsed by the Creators and became the official ARG of lonelygirl15.
