Texhnolyze is a fantastic, brilliant and unfortunately underrated anime that comes from most of the staff who worked on a similarly dark anime Serial Experiments Lain.
The plot is as follows: Lux, the name of the underground city is ruled by gang warfare, all aiming for more and more control of the decaying city that is Lux, and the technology of Texhnolyze (allowing the use of robotic limbs in humans). The story follows Ichise, a young man who spends his life fighting in underground fight clubs, Doc, the creator of Texhnolyzation, Onishii the leader of Organo, Ran, a young girl who can see into the future and Yoshii, a mysterious visitor from the surface world.
Unlike most anime, Texhnolye is very experimental, (with very little or no fan service whatsoever) and this is often seen in the dramatic angles, fight sequence, explicit violence and even in its soundtrack, which itself, is a mix of acoustic, electronic and orchestral music which suits the show very well.
Texhnolyze is thought provoking series, often characters will talk about the nature of humanity, man's ego, the effects of technology on humanity, power, greed, redemption and salvation. Although you might think the characters talking about these subjects could be out of place in the anime, it is not and fits naturally within the scene.
One of the flaws of Texhnolyze (and this is one echoed by many) is that the first few episodes (particularly the first episode) are not very interesting. For example, in the first episode, barely 3 lines of dialogue are spoken. It's something like that that can turn most people off the anime instantly. Unfortunately for Texhnolyze, it is a slow burner, and it can take a at least four, maybe five episodes before it really draws you in. But when it does, it doesn't let you go.
I encourage everyone to see this series and most of all, give it a chance, because this piece of art deserves to be seen.