Alternate Reality Games, a.k.a. ARGs, are for sure a hard thing to define.
Aristotle said with his ancient wisdom: “don’t try to define an ARG, better show a couple of examples”
Before that, I’ll like to show an image that, in my opinion, is ARGs in a nutshell (stoled from Andrea Phillips)
Alternate Reality Games
Now we can answer: what is an ARG?
The answers, in no particular order:
Zona Incerta (portuguese)

Buen intento de explicación! Aristóteles la tenia clara.