Darker than Black: Kuro no Keiyakusha, Dimension W Recommendations
The author of Dimension W was the character designer for Darker than BLACK, and this little fact seems to explain why there are so many striking similarities between the two series: DW is probably best described as the author's very own edited version of DtB.
Firstly, there is DW's dead-eyed, knife-rope badarse lead with an initially mysterious past as a soldier in a fictional war; currently finding himself working as something of a jack of all trades mercenary. Then there is the main plot involving a largely unexplained supernatural phenomenon that allows for all kinds of episodicness, such as even a ghost murder mystery story.
They both share the same author (Iwahara Yuuji) and generally gives off the similar vibes. The MCs even attack in a similar fashion of throwing knifes attached to ropes.
they are both Sci-Fi, and well, just give the same kind of feel in general.
The main characters in these shows are extremely similar when it comes to to their combat abilities and personalities. There is also mystery behind both main characters and worlds they live in.
Darker than Black is essentially the better version of Dimension W. The character designer for DTB is the writer of Dimension W, the protagonist is a taciturn bad ass who fights using knives and ropes, with a troubled past, and other similarities that would spoil the story. Seriously, just watch DTB.
Both have a somewhat sci-fi setting (though DtB is more fantasy-like), and both have a main character who uses wires to fight. They're also both fairly dark and are both seinen.
Also, the character designer for DtB created the manga of Dimension W.
Have a same feel and atmosphere.