Instead of going the traditional fantasy route, .hack//Sign is set in the world of a popular MMORPG, The World. The main character has no interface and is unable to log out, and the rest of the party members accompany him in the game (and work outside the game as well) to try to figure out what’s going on.
I watched maybe half of the series before giving up. It’s placed very slowly, and because Bandai chose to integrate it closely with their .hack// video game series, it’s impossible to get the entire story just by watching the show. Stupid cross-media properties, making entertainment work.
I did like the music, though; this was the first time I’d come across the work of Yuki Kajiura, and she’s been one of my favorite anime/game soundtrack composers since.