Some thoughts on your work
Accepting that you have noted an existing gender choice i.e. Alex/Rebecca Walker it is not good practice to continue this on throughout the document in the style of "his/her" as this interrupts smooth flow of text, better to simply select one gender for use in delineating the outline after having recognised the capacity for gender choice in the beginning or alternatively use non-gender specific terms such as the character (or the player) will have to face their past as a Shadow Ranger etc. Unless you are planning to diverge the character roles from each other substantially due to different genders it is fairly unnecessary to bring it into focus at this stage of development.
A new resource called the Derectus has been discovered....I am left confused as to the nature of this resource given its capitilisation which leads to impressions that the form of resource is less likely to something like coal or oil but rather an AI or an ancient library or even a derelict spaceship or a military force suspended in stasis. The fact that you don't mention it further in your document almost trivialises its existence yet I am assuming this will be the resource and the control of said resource upon which all the interactions in the game will lead to.
The hybrids remind me of the reapers from Mass effect i.e. part organic/part synthetic life forms that routinely cleanse the galaxy of sentient organic life in order to save the galaxy.
The Galactic Dominion being a fascist collective interests me in how you will balance the xenophobia towards others outside of the collective while providing a legitimate argument for that same form of xenophobia not tearing the three races comprising the Dominion apart.
The UCSG are extremely nationalistic. I will be interested to see how you offset this against the Dominion's government which is also another form of nationalism.
Voice of the Milky Way. Anarchistic factions are tricksome to play with as you usually have multiple interests with their own agendas working together for a common purpose i.e. you can have situations such as the enemy of my enemy is my friend until my enemy is dead and then my friend is the enemy. You might observe a high degree of organisation in some of the interests that comprise the VMW and at the same time you might also find a bunch a rebellious grannies whose contribution is to knit doilies with inflammatory slogans.
AT the end of the day - what you have is very much a beginning but giving feedback on a limited piece of work is difficult when the scope of the game is not outlined very well. I would be more interested in the seeing plot rundown you are working on