I'll begin the discussion of the writing in Galactic Civilizations II with two factions that are seminal in the development of the immediate background of the game's universe: the Drengin (DREN-jin) and the Arcean (AR-seen). factions that begin the back story, at least on the wiki. I am no expert on structure or writing, but I am not half bad, and analyzing the bad is a fantastic why to learn what makes something good.
Drengin
Ostensibly, the Drengin are a cruel and deceitful empire. They are said to be both incredibly evil and clever at the same time. Their society is supported via the use of 'slavelings', and they are keen to use other species as such. Even their technology is researched by slaves. They are often characterized as 'clever' in their evil plots.
Comparable Species: Cardassians
Arcean
The Arcean are basically drawn as a foil to the Drengin; they are of a similarly warlike stock, but are more honorable warriors of tradition and galantry instead of warmongering overlords. The flavor text describes them as being "[not] evil, they just don't care". That is fairly vague in terms of their actual values, so I will assume that it means that they just act based on an alien morality, with an emphasis on honor and power. They want to control the galaxy and seem to think they are the perfect species to do it.
Comparable Species: Klingons
The Arceno-Drengi War
Eons ago, the Drengin and Arcean came to blows; unsurprising since they both have a desire to be galactic conquerors. Together they constructed the first stargates, some 300,000 yaers ago, but the devious Drengin decided to start a war with literally the only other superpower they knew of in the galaxy. In 98,000 B.C.E..
The Arcean, being ready for them, deactivated the stargate on their end in the middle of the Drengin fleet's traversal, stranding them halfway to the Arcean homeworld. The Arcean then destroyed the invasion fleet, and the two species went their separate ways.
The Drengin Enslave the Tori
In an unexplained manner the Drengin locate the fledgling Tori species; semi-aquatic and peace-loving. They construct a stargate and send it hurtling through space towards Toria. 70,000 years later the stargate arrives and the Drengin swarm through it, conquering the Tori easily. Some 26,000 years later, the Tori realize that maintaining a strangle hold on Toria through a stargate is expensive and that the Drengin must be over extended, and a surprise attack manages to kick the Drengin out of Tori space.
The Arcean Attempt to Trick Humanity, Screw up the Galaxy Instead
The Arcean run into the Altarians at some point, but the relationship becomes one of mutual respect, or mentorship. Eventually the Arcean come across the Sol system, and send Humanity the plans for a stargate of their own. Of course, with their eyes on conquering the budding race instead of allying with them, the Arcean's plans have no method to turn off the gate once activated.
Humanity does not notice this detail, and instead focuses on the physics and technology implied by the design. Since they have already developed fully functional nuclear fusion, they are in a position to make the spatial warping mechanisms of the stargate into a portable device. They do so, and construct the first Hyperdrive. They quickly disseminate the design to the entire galaxy, effectively creating an arms race of colonization and military buildup.
Interstellar Travel: It Can't Work That Way
There is a huge problem of timescale, here. In 298,000 B.C.E., the Arcean and Drengin make contact and design the first stargates. That figure is taken from the fact that the Arcean and Drengin meet before Homo Sapiens walked the earth plus a hundred thousand years. 200,000 years later, in about 98,000 B.C.E., the Drengin start a war with the Arcean which ends badly for the Drengin.
When the two part ways, things start to get very odd indeed. The Drengin discover the Tori; since there is no stargate to Toria, they must have found it via exploration. It was by unmanned probe, and it occurred some 100,000 years ago. 70,000 years later the stargate arrives and Toria is enslaved.
Arcean and Drengin: Problems
The major issue here is that the Drengin have never demonstrated any cleverness and the Arcean are not shown to be the stubborn, honor and tradition bound race they are supposed to be. Their dispositions as presented are quite the opposite.
The Drengin attempt to invade a far flung star system by simply sending it a complete stargate, which is slow and error prone and certainly not clever. The Arcean take the sneaky approach and send only the plans, allowing the target to work themselves half to death to build a device that will spell their own doom. Drengin come off as arrogant and brutish, while the Arcean have a candid and diplomatic approach. The Drengin have crappy diplomacy, which no clever race would have. It must also be mentioned that the write ups for the unique Arcean techs characterize Human engineering as not being clever enough.
Then we have the problems of distance and travel time. We know that a stargate allows travel at 0.165 light years a week. This is a fudgey measurement since it is adjusted for the warping of spacetime (yay plot devices). That means that one year in a stargate journey translates to 8.58 light years. We know that Arcean space and Drengin space are one year in a stargate separate from the Artificial Gravity tech flavor text, and that is likely between homesystems. Problem is, when the Arcean deactivated the stargate on their end, the Drengin fleet were trapped thousands of light years away from home. Even if adjusted parsecs are for the benefit of the star map and reperesent a full 3.26 lightyears in unwarped space, that still leaves Drengi and Arcea only 169 lightyears apart.
What's worse, the Arcean Empire manages to not only trap the Drengin fleet in the middle of nowhere, they get out to that fleet and crush it in a timely manner. Quite a feet for a species who has a stated penalty to interstellar travel. And if a Stargate can be deactivated in the middle of a journey safely, why are they still only point-to-point devices? Seems like a cleverly designed network of gates would allow you to travel to most important system fairly quickly if you can turn the gate off in the middle of a journey.
So after that debacle, which among other things implies that the Drengin never arrived in the Arcean systems even though that same tech flavor text insists that they did, the Arcean never open their stargate to Drengi again.
So what? The Drengin immediately after their defeat find the Torians and send a Stargate their way, fully constructed, and wait 70,000 years for it to arrive at Toria, a figure the Drengin are more than willing to accept. That means that the Drengin would only have to travel at a speed of 765 kilometers per second to reach Arcea in the same amount of time in the worst case scenario of distance. That's only about 50% more than the escape velocity of our solar system. If the Drengin are so patient, and have the resources to build a stargate only to send it off to invade a planet in several millenia, why didn't they just attack the Arcean Empire again?
In all of this, no mention is made of exactly, or even vaguely, how interstellar communications work. They seem to be instantaneous, though space travel is not. And that brings up another issue. The Arcean find Earth and send plans to a stargate through their remote probe. How long did all of that take?
Well, when the humans recieve the plans, they invent Hyperdrive and give it to everyone. By that time, the Torians have long been independent, so it has to be more than say, 140,000 years as the Drengin had to discover the Torians and that would take at least 70,000 years. We also know that traveling via the stargate to Arcea from Earth will take 10 years, so the two are separated by 86 ly or 1695 ly. Now, assuming the Arcean home system is similar to Sol and the probe is somehow able, after a very long journey, to manuver for orbital insertion into Earth's gravity, and with the benefit of instantaneous communications, but with finite fuel supplies and conventional propulsion, it'd be traveling at maybe 525 km/s (the escape velocity from our solar system relative to the Milky Way). If we stick to adjusted parsecs being full parsecs in unwarped space, then it would take the Arean probe 1.02 million years to get to Earth.
In context, 1.02 million years ago was just after the extinction of Homo Erectus. In the GalCivII backstory, its about the length of time it took Humanity in a very recognizable form to invent Hyperdrive. It also means that between the time of the expulsion of the Drengin from the Torian systems and the time of the game, 860,000 years had past.
I'm not sure this makes any sense. Are we supposed to believe that a mortal alien species can afford to wait a million years to interact with another species and still be interested in conquering them? Or even 70,000 years? And what were they doing that whole time? If Humanity managed to discover and perfect fusion technology in perhaps half of the time the other important species have been around, why didn't those species figure it out themselves?. It seems highly impossible that a space-fairing race would spend that much time hanging around, waiting for probes to report, and not once become curious about how stars make energy and at least attempt to replicate it experimentally. And no argument of a lack of curiosity is valid, since the Arcean have space probes that work thousands of light years away and over millions of years. They are guilty of curiosity by association with such exploratory devices.
On top of that, these races had become accustomed to plotting things on a geologic time scale, and suddenly, with the power of Hyperdrive, they become capable, and very eager, to develop at a more Human pace. They even reproduce at a competitive rate, which is odd since the Humans live on such a hastier time scale it would be reasonable to assume that they could out-reproduce the other races.
Finally, we need ask how exactly the Drengin and Arcean fought battles in space without having any space weapons. You need to research these weapons in the game, so how the Arcean fleet wiped out the Drengin fleet in deep space is a serious question. Since energy production is the primary stumbling block in the game's narrative, one would assume missile weaponswould be the standard arms until the power needed to run rail guns and energy weapons was available, but we do not see this and the game's AI actually has a tendency to avoid missile technologies.