Essentially, Deus est Machina is what you get when you tell Zenith to create a story based entirely on non-sexual Author Appeal. It's been described as a "techno-punk science fantasy influenced by Christian and Hebrew mythology that takes place After the End".

The story takes place in a floating city of alabaster called Heaven. In Heaven, robots called Angels keep order and protect the populace, which consists of the descendants of mankind. The commanders of the Angels are the seven Archangels; at the start of the series the group consists of Michael, Raphael, Uriel, Sealtiel, Metatron, Jegudiel, and Barachiel. The Archangels are extremely robotic in nature, and are made up of different pieces. The rest of the angelic choir works behind the scenes.

It's revealed fairly early on that the world Heaven is floating above is a future Earth. A far, far future Earth.

The story revolves around a few characters; none of them are really the main character. Sariel is not important to the overall Myth Arc, but her actions cause important events in the long run. Lucifer is the commander of the Angels, second only to the Archangels; he questions the tactics of Michael and uncovers some pretty horrific Ancient Conspiracies. Gabriel is Sariel's long-time friend who has to contend with the fact that someday one of the Archangels is going to die and he will have to ascend to the position, losing his "humanity" in the process. Joshua is a teenager who was frozen due to an incurable illness; he wakes up in the devastated world and decides to help the survivors, becoming the Messianic Archetype in the process.

What Do You Mean, It's Not Symbolic?

Note: has nothing to do with the actual trope Deus est Machina.

Tropes

• Fallen Hero: Lucifer. He actually chooses to fall rather than uphold the Ancient Conspiracy set by Michael; he takes the humans still on Earth and creates a new world on the planet, which he calls Sheol.
• Foregone Conclusion: Lucifer is a main character. Naturally, he has to fall at some point. Gabriel becoming an Archangel is also one, both in-universe and otherwise.
• Killed Off for Real: Joshua succumbs to his illness about three-quarters of the way through the narrative.
• Man Behind the Man: Azrael, who was the one who set up the Ancient Conspiracy and has been subtly influencing the Archangels from behind the scenes.
• Myth Arc: While the work is divided up into "books" centered around specific characters, there are several underlying story arcs that form one of these; components include Lucifer's destined Fall, Michael's past, and a legendary Archangel called Azrael.
• Pinball Protagonist: Sariel. She gets more time focused on her as a protagonist than the other characters, but overall she just kind of gets shoved around by the plot.
• Puppet King: Heaven actually has a human leader, but they're typically ineffectual and the real power belongs to the Archangels. One part of the story centers around a leader who begins to gain actual power in Heaven. He is poisoned by Azrael to keep The Masquerade.
• Ridiculously Human Robots: The Angels. They're actually humans who are taken at birth, raised in seclusion, and eventually mind wiped and outfitted with robotic parts.
• Spanner in the Works: Joshua, constantly. Nobody was even aware of his being alive until he started screwing over plans left and right.