So far, I've pulled in a lot of influences from films and TV shows such as Star Trek TNG, Star Wars and Babylon 5. I've also thrown in some sprinklings of Gibson to show the seedier side of humanity in the high technology society.
As it stands, I have several major factions, each of which have origins in the Sol System:
There's the Sol Systems which are as an Oligarchy by a President and his council of advisors. There is some form of democracy going on, but the advanced technology and wealth of the Sol Systems means that its populous wants for nothing. Generally peace-loving, the inner Systems know nothing of war and are oblivious to the existence of any other powers in the galaxy. However, after being held to ransom by the UTF the Sol Systems have been forced to develop their own methods of long-distance galactic travel. The primary aim of this power is to expand whilst still maintaining the high quality of life for all of its members. As such, expansion is often slow as only the best worlds are colonised.
Originally founded by miners and traders, the United Trade Federation formed the extensive trading and mining outposts and links across the galaxy. The UTF initially supplied the Sol Systems with the resources and wealth it needed to develop into what it is today. However, the slow expansion of the Sol Systems frustrated the UTF, causing them to cut their ties with Sol and govern their own systems, which are often bleak, harsh environments with little appeal other than their resource value. The UTF were forced to develop their own R&D and military arm after cutting from Sol, meaning their technology isn't as advanced. However, years of living in harsh environments has caused the people and technology of UTF to become more hardend.
On the border of the Sol Systems and the UTF are the disputed worlds. The disputed worlds were initially formed after border disputes caused millions of refugees from the UTF to pour into Sol Systems space. Sol were resistant to accepting them as the people were said to have been 'corrupted' by the nature of the UTF worlds. Fearing a culture crisis, the disputed zone was formed and the borders to the Sol Systems were closed. As these people were attempting to flee from the UTF, they were persecuted by their former governors, forcing Sol to intervene and stop the humanitarian crisis. Outraged by the interference, the first Sol-UTF war began. Today, the disputed worlds act as a buffer between the two powers and with neither side willing to stake a claim they claimed independence. The disputed worlds are largely lawless and are extremely resentful of both major powers, a fact that is exploited heavily through funded acts of terrorism against either side. The technology obtained by the disputed worlds is largely 'donated', salvaged and stolen from the two main powers, leading to a strange mix of ships and buildings. Being vastly underpowered, the disputed worlds often resort to underhand and extreme methods when fighting and can do so without fear of a major retaliation from either main party (due to the other declaring war on them).
There are, of course, other 'races', such as the Cybernetiks but I'll talk about them some other time...
The Hydra game will see you as a pilot belonging to a group of rebels/terrorists from the disputed worlds launching Sol-Systems sponsored attacks on the UTF's supply routes. Manta-X will be similar, except you'll be fighting for another faction...