.hack//SIGN is when the world is stuck in games... not just playing, but actually someone got caught in this thing. The reason? Somehow in the programming of this game, code was written to be able to get someone's consciousness stuck in the game. If you're an observant, careful viewer, you'll be able to discover the why (but sadly for your geeks, not that how).

I don't believe I've seen a more mysterious yet clean anime.
Spoiler: The only "nudity" would be the exposure of the chest area of female avatars, nothing more.

The story is very intriguing, especially if you walk in on it halfway. (Doing the latter makes several scenes that look possibly spiritually bad, mystical, or scary, unless you know what's going on.)

Violence:
At a minimum. On a rare occasion, a character here or there falls, but since everything is in a game, no one dies and there's no blood.

Directing and soundtrack:
The directing keeps things mysterious, hiding important details, and the music follows along making things weird.

Who could watch this: Just about anyone.

Did I enjoy it:
Most certainly. Would I rewatch it? With friends, probably.

Note on Sexual Content:
A male and a female character in-game grow close but in real life both players are female and once they meet outside the game, it's hinted at that they start a relationship. Absolutely nothing objectionable is shown on screen.

The English dubbed version of .Hack//Sign. This is a very well made series. The musical scoring and the environments were both well designed. This title has little violence. The violence is limited almost exclusively to game violence with no blood. This is overall a very clean series. The isn't any true nudity. The intro implies nudity during it without showing anything. Tsucasa is a player can no longer log out of the game. Tsucasa is given a guardian and taken to see a place to see a sleeping girl. The story builds as events in "The World" continue become more strange. The players begin to seek the Legendary "Key of the Twilight."

This show is particularly interesting because although you mostly only see the characters "in-game" it is really about who they are as people outside in the real world.

But the most awesome thing about this anime is the music: amazing electronic world-beat folky wonderfulness, in both Japanese and English. Get both albums--you won't be sorry. I buy this music as presents for people who would never watch the anime.