I completed the last campaign on Supreme Commander today (with the cheats on) and I have to say I am a little disappointed with the story. SC has three great factions to choose from each with a six planet campaign, firstly there is the United Earth Federation who is a Republic that was formed after the Galactic Empire fell. The Cybran Nation is a group fighting for the freedom of enslaved cyborgs led by their creator Professor Brackman (who is now over 1000 years old). And then there is the Aeon Illuminate, religious nuts who happen to have really advanced technology left to them by an alien race that founded their religion.
There are sparks of genius in the story. In-partially the Cybran Nation resembles a struggle for racial equality, like that between Malcolm X and the Nation of Islam where instead of unity the Cybran Nation (just like Malcolm X did in his early years) seeks racial segregation as a means to end tension.
Dialogue is done with an emotional alignment that makes you see things from the view of the faction you are currently fighting for. So if you are fighting for the Aeon Illuminate their commanders come across very ethereal in their caring for the civilian population, but play on the side of the United Earth Federation and they will seem like religious zealots. Then play on the side of the Cybran Nation and they will appear to want to cleanse the universe of all Cybrans. This works quite well and no faction seems more evil or good than the others after playing through all available campaigns.
The story however isn't very interesting and the Aeon Illuminate especially seems very unsound as the game doesn't fill in any gaps to help the player understand what this religion they follow actually is. More details about the planets that the player fights on would add more depth to the universe. More information about the factions as the game progresses would also be welcomed as with the Aeon Illuminate and United Earth Federation I found myself not caring wither they won or lost. I did however care about the Cybran Nation, but that was only because the Aeon Illuminate commanders kept calling the Cyberins abominations and that made me identify with them a little as I also get that from religious groups from time to time.
Overall Supreme Commander has an ok story, but it could have been much better if it had just given more information about the universe, what was going on and tried a little harder to make me care about what happened to the different factions.
If you complete the game, watch through the end credits (you actually have to watch the whole credits) and you will be rewarded with a five second FMV sequence after the game results screen which indicates that the game's story isn't over just yet, not that you are given much of a reason to care, but I still look forward to an expansion or something that will build on what groundwork was been laid-out.