"An alternate reality game (ARG) is an interactive networked narrative that uses the real world as a platform and employs transmedia storytelling to deliver a story that may be altered by players' ideas or actions.

The form is defined by intense player involvement with a story that takes place in real time and evolves according to players' responses. It is shaped by characters that are actively controlled by the game's designers, as opposed to being controlled by an AI as in a computer or console video game. Players interact directly with characters in the game, solve plot-based challenges and puzzles, and collaborate as a community to analyze the story and coordinate real-life and online activities. ARGs generally utilize multimedia, such as telephones and mail, but rely on the Internet as the central binding medium.

ARGs tend to be free to play, with costs absorbed either through supporting products (e.g., collectible puzzle cards fund Perplex City) or through promotional relationships with existing products (for example, I Love Bees was a promotion for Halo 2, and the Lost Experience and Find 815 promoted the television show Lost). Pay-to-play models exist as well. Later games in the genre have shown an increasing amount of experimentation with new models and sub-genres." (The Alternate reality Game page from Wikipedia.)

Although most ARG's are of the horror genre, it is not a requirement.

Currently this tag is only used on an abandoned project by pegacousin, and certain posts by Sealled.