This document provides an overview of alternate reality games (ARGs). It defines ARGs as interactive narratives that use the real world as a platform and involve player participation to help shape the story. Examples are described such as The Beast and I Love Bees that had millions of participants working together online to solve puzzles and advance the narrative. The document outlines key ARG elements like puppetmasters, the curtain, rabbitholes and trailheads. It also discusses the history and influences of ARGs as well as challenges facing the genre.