I've been saving a replay of this VN for years.  My original opinion on this VN was excessively influenced by the fact that this VN is filled to the brim with Masada and Dies Irae worship.  However, it is also the VN that, separate from that, defined the second Light team's style.  The base character archetypes, roles, and numerous aspects of their settings were almost universally drawn from Dies Irae, if you strip away the specifics.  This is the biggest reason I had so much trouble properly rating this VN the first time around.

First, I should mention what is perhaps the most defining element of this team's VNs... there is at least one Mercurius/Reinhardt type in every one of their VNs.  I don't mean in the specifics... but in the sense that those two were 'spontaneously generated absolutes'.  Both Mercurius and Reinhardt were characters who, at the core, were already 'complete' from the beginning.  In each of this team's games, there is at least one character of that type. 

The reasoning for including such characters is probably because 'absolutes' tend to create powerful emotional reactions in people and naturally become catalysts for conflict.  As a tool for progressing chuunige stories, they are an ideal element.  Since these characters are transcendent from the beginning, they tend to change very little during the progression of the story, further pinpointing their role as catalysts.  I could name each such character for you, but I'll limit it to this game... Akizuki Ryouga. 

Akizuki Ryouga is the protagonist of Zero Infinity, a young man who has a rather... unusual philosophy and a mentality that is like that of a person born already close to achieving enlightenment.  Quite naturally for a chuunige, he gets dragged into an underground war between powerful cyborgs called Imaginators, rebels and hunters from Holologium, the organization that rules the world.

The setting is 1967 Japan.  The Japan of that era had achieved a 'miraculous' economic recovery after WWII and was approaching its peak, its population recovering rapidly from the loss of the previous generation. 

The structure of this story is identical to Dies Irae's, at least in how it handles the route order.  It gives you a choice of two 'initial routes', and if you finish one you can access the route of the first main heroine, whose path reveals the truths ignored or left untouched in the first paths, and after you finish the first main heroine's path, you can complete the second main heroine's path, where all the loose ends are tied off and you get an untainted good ending.

Now... one thing I love about this game is the way it humanizes the antagonists.  Setting aside the antagonist who is a heroine (Elizavetta), Ivan Strigoi, Alexandre Raskolinikov, and even Apollon leave a powerful impression.  Ivan is the only one I can talk about without spoiling things to a ridiculous degree, so I'll focus on him.

Ivan Strigoi is something of a tribute to the Einherjar of Dies Irae (all the characters are tributes to Dies Irae ones... lol).  He is a man wrapped in bandages who has lived his entire life on the battlefield.  He is a believer in the value of heroism and loves those who strive (both in war and in everyday life) above all other things... including those who he kills or try to kill him.  Like Elizavetta, he is also a former Soviet soldier, turned into an Imaginator after death and recruited into Gears to hunt rogues.  I'll be straight... this kind of smiling warrior who loves with a passion all those who stand on the battlefield with resolve never once brought out negative emotions in me, despite all the crap he put the protagonist's side through.  It is just so hard to hate him, lol.

As for the story itself... well, it is a Light chuunige.  Stripped of the irritation over the excessive tributes to Dies Irae, it is actually right up there near the top.  After all, this is the team that made Vermilion Bind of Blood and the Silverio series.  I will say that this game is significantly better balanced (lol to anyone who has read this VN) than the Silverio series, as that one put so much emphasis on the main/true paths that the neglect became painful in retrospect.  That said, its flaws are actually glaringly similar to a lot of the greatest of chuunige... the antagonists remain in your memory more strongly than the protagonist and heroines, lol. 

Years after playing this the first time, I still remembered Alexandre and Ivan clearly, even though my memories of the heroines were getting blurred... and that is fairly typical of my experiences with a lot of the better chuunige out there.  There is something about the genre that demands a strong set of antagonists to bring the story to life, which is why chuunige with pathetic antagonists tend not to remain in memory.

Anyway, this VN's theme is more than a little painful for anyone born into modern society.  The characters are rather blunt about their feelings about where society is going as a result of scientific progress, and it plays pseudo-prophet when it comes to the effects of the internet on people's psyches.  As such, the first reaction of some people when it comes to the philosophical ramblings of the characters (an inevitable side-effect of this being a chuunige) will probably be more negative than is the norm. 

I could spend several days analyzing this VN... but I'm going to stop here.  For people who want a heavy chuunige, this is a good choice, but I wouldn't recommend it for anyone else, since it is  so blatantly a chuunige in every particular.