“Asynchronous ARGs” that’s what I call ARGs that anyone can play because they don’t have to catch up with the story line. Unlike a story-based ARG, that can be told as a tale only after it has finished.
For example, ARGs that are advertising something (i.e., a film, or a game) their goal is to satisfy curiosity about the product and add some “bonuses” and/or solve some puzzles/problems along the way. is accessible to anyone who has a link to the starting point or sometimes called a “rabbit hole” (via website, twitter, youtube, Facebook, instagram, flikr etc.).
If you are interested in creating an ARG see Getting started with ARGs from ARGNet.