Gilgamesh

Both are dark cyberpunk series with very similar pacing. Texhnolyze has stronger violence, and the characters are not as likeable, however both shows provide a slow and steady ride to the end. 

Easily, the first anime I've watched since Texhnolyze that gave me a similar experience of heaviness and darkness. An endless train of misery, culminating in utter despair. Besides this, both have great and original storylines, revolving a lot around character development. Whereas Texhnolyze however manages to vary its atmospheres and vibes, from heaviness, philosophicality, depressiveness to action, Gilgamesh has a tendency to slow down and dramatize almost everything - the virtue is they're really good at it, the vice they use it way more than they should and for pointless things too, things like Death Note's famous chip scene. Is it on Texhnolyze's level? No, Texhnolyze is a masterpiece. Is it worth watching if you enjoyed the heaviness and darkness of Texhnolyze? Very much. read more 

Texhnolyze isn't sinister, glacially slow and heavy enough for you? You want more mature storytelling, post-apocalyptic misery and utter despair, bleak nihilism, murky colors and 2000s CG style? Then G (while not quite T's league) will get under your skin. Gilgamesh = Texhnolyze atmosphere - action + Darker Than Black setting. 

Both shows take place after an otherworldly phenomenon changed life as we know it. In Darker than Black, it's Hell's Gate, in Gilgamesh, it's Heaven's Gate--go figure. The associated phenomenons are directly related to certain individuals acquiring mysterious powers. Darker than Black is brighter and more entertaining than Gilgamesh and the powers are much more interesting and varied, but the setup is similar. 

Both Darker than Black and Gilgamesh begin when a large-scale disaster changes the earth's sky (in Gilgamesh, it becomes reflective; in Darker than Black, a fake sky with fake stars appear, from where shuttles do not return), and, for some reason, gives certain individuals super-powers. Both series are heavily focused on city-life, and even share the name of where the incident happened, Heaven's Gate, though Darker than Black goes one further and adds a Hell's Gate to the mix. Both are action orientated and have a dark, cynical atmosphere, culminating in the characters ultimately questioning the future of humanity. However, notable differences are apparent. Whereas Darker than Black focuses on action, Gilgamesh focused on unravelling the mystery behind the superpowers. Darker than Black is more recent and has a better quality animation, whereas Gilgamesh is stylistically ugly and minimalist. The characters in both are pretty dissonant from the audience, but Darker than Black has some character-to-character humour sprinkled throughout, whereas Gilgamesh has none. Both have excellent dubs and are worth watching if you enjoy mysterious conspiracies, explosive action, quasi-scientific babble and super-human abilities.  read more 

Both shows use a very similar world and scenario. In both a dimensional door named Heavens Gate opens and humanity's dealing with this leads to a world-changing global catastrophe. The sky is scorched and there are mass fatalities. As a result of the event, super-powered individuals appear among the humans. The stories themselves are quite different. Gilgamesh is dark and psychological, while Darker Than Black is more action oriented. And despite DtB having "dark" in the title, it's by far the "lighter" version of the scenario - which says something about how extraordinarily sinister Gilgamesh is. 

Both are excellent gothic-style Anime with similar thoughts/questions about human beeings 

They are both inspired by mythology and have supernatural creatures and they have the same mood and color palette , and the graphic is somewhat similar.  

Both shows are dark sci-fi with heavy mythological motifs, stylish art direction (Gilgamesh has no budget, but the attempt counts) and atmosphere. The main connection is the narrative technique. Both shows tell a linear, chronological story without too many flashbacks. Yet, the underlying mystery is unraveled glacially slow, so information required to understand the actions one witnesses are lacking at that point. In Ergo Proxy this is more massive and pretty much requires a re-watch (or being spoiled beforehand). Gilgamesh is less extreme, but it still requires full attention while watching. Also both shows use symbolism a lot. 

Both take place in a post apocalyptic world. The series once watching are very similar. Both animes have the Fathers playing a big part and both kinda neglected the main characters, mothers are deceased, and the child ultimately has to make the decision for the fate of the world. The Gilgamesh like the Angels have to be fought to save humanity, and they have characters with deep emotional problems.  

Gilgamesh is a visible anime based in some NGE aspects. It even makes an explicit reference to NGE in first episode. In NGE Seele wants to be God, in Gilgamesh is Enkidu and his followers. Both have a GREAT character development, emotional scenes that touch, the stories are similar and have many expects in common like clones, world catastrophes/post-apocalyptic. Others elements in common are humanity feelings and psychology, 2 different sides: the one that wants a world revolution/evolution and other that wants the world how it is. Even the finals have something in common, both are unpredictable and "choking". Gilgamesh is very slow paced, so you must have patience in firsts episodes at least. read more 

Also a post-apocalyptic anime with a mythological / metaphysical science fiction framework. Both strong in psychological, inner turmoil and struggle. Many similar themes regarding supernatural-powered enemies, human power factions with particular agendas, scientific research (e.g. subatomic physics, bioengineering) and philosophical considerations.