Alternate reality games (ARGs) are commonly misconceived as videogame tie-ins for films, virtual worlds like Second Life (Linden Lab, 2003) or online role-playing games like World of Warcraft (Blizzard Entertainment, 2004). They are none of these things, but their precise definition is hard to pin down. A good definition is provided by designer Andrea Phillips:

In these games a cohesive narrative is revealed through a series of websites, emails, phone calls, IM, live and in-person events. Players often earn new information to further the plot by cracking puzzles … players of these games typically organize themselves into communities to share information and speculate on what it all means and where it’s all going.1