I think this game still has the problem with scale. Being limited to "just the Milky Way" still means 400 million star systems out of which at least 4 million of them are somewhat habitable, not to mention technologies which could allow you to settle on lifeless star systems. Add the fact the Orion Empire owned nearly half of the galaxy, it can lead to rather weird consequences. Similarly I don't feel the FTL is really something you'd consider slow, albeit limiting to only these two is a good idea to help making a more consistent setting.

This is why it's encouraged to rather take a tiny slice of the galaxy as the "map" and perhaps even slower FTL with gate travel providing the "fast enough to be convenient" method. But I digress. There are a myriad of sci-fi stories that fail to take the sheer scale of the galaxy into account. Why should we? I'll try to think of this more like Star Wars than say Mass Effect or especially anything more serious.

Anyways, I might at least try to join as my Martian faction. They're going to be inspired by the War of the Worlds book and 50s sci-fi with some modern influences. Would it be okay if my history involves the Martians trying yet failing to invade Earth?
The story would be that the Martians fled to the distant corner of the galaxy with a primitive warp drive and by the time they have arrived humans already created their Orion Empire. So they are now all too eager for revenge as the mighty empire collapsed.

EDIT: Oh, we have human Martians? That's going to be fun. My species are referred as the Martians but they are more properly called as the Sarmakth. The conflict between the "fake martians" and "true martians" could be fun.