1. A condition in which someone is so in love with a game, movie, etc. that they wish they could live in the fictional universe that game or movie takes place in and are brought down by the realization than they can not.
2. A condition in which someone is so in love with a game, movie, etc. that they wish they could be the central character of that piece of media, and are disapointed thinking their lives suck in comparison.
(Common causes): Avatar (film), Mass Effect, D&D, WOW, Star Trek.
Guy 1: Hey dude whats wrong?
Guy 2: I was just thinking, nothing seems to come close to being as amazing as anything on Pandora.
Guy 1: I think you may be suffering from a bad case of Avatar nerd depression.
Guy 1: Hey dude can you cover for me at work?
Guy 2: Commander Shepard doesnt have to cover for his Co-workers! He saves the galaxy then sleeps with Tali!
Guy 1: Holy shit dude calm down! looks like you got a bad case of Mass Effect nerd depression.