The Flood is not some stupid parasite. It has a center. A mind. And it has spoken to us, laughing. We are not the first. It has done this before, elsewhere...
Ancient Forerunner Log
Millions of years ago, a parasite took a grip on the universe. It was known as, "The Flood". Each enemy that fell joined its ranks, and the infection spread. It was unstoppable. All the space faring races that fought were consumed, and those that ran were only delaying their fates. Every 16 hours, another planet would be taken.
The Forerunners had been the ones to unknowingly unleash this terror. They were the most advanced race in the universe, and they had prepared for an outbreak such as this. It was an absolute last resort, and so a thousand other plans were tried, and all failed. Billions of men and women fell before only one option remained.
The last of the Forerunners, possibly the last intelligent beings left in the universe, retreated to The Ark. It was here they would hide, and from here, they activated the 7 Halo's.
Great waves of energy coursed through the galaxy, destroying any creature with sufficient intelligence and body mass to sustain the parasite. How this was done, we do not know. How the Forerunners survived in the Ark, we do not know.
But the universe was picked clean. There were no hosts left. the parasite starved to death.
Emerging from the Ark, the Forerunners began to rebuild.
They had survived a genocide that had continued long before their time. The universe had fallen to the parasite many times before. With the Halo's, they had managed to break the cycle.
Now, it is the year 2525. Humans have advanced and colonized the universe. Known as the UNSC, they have become locked in a devastating war with The Covenant, a ring of fanatical alien races who have been led to believe the humans extinction is the will of their Gods, the Ancient Forerunners.
Little do they know, the humans are the Forerunners descendants, "The Children of the Ark" when their war brings them to accidentally unlock a pocket of hibernating Flood, the Covenant cast down their leaders and form an alliance with the UNSC. Led by The Prohpets lies, they had wrongfully burned the humans worlds, killing countless innocents.
Now the war is over, and an even more deadly foe must be faced. The Forerunners had barely managed to save themselves before. Could it be stopped again? Or will The Covenant and the UNSC fall, as countless empires have in the past.
Take up the Plasma Sword and fight for Sangheili pride as an Elite.
Become the unstoppable power of a Spartan super soldier.
Put on the boots of a simple human Marine
be the Captain of a massive UNSC vessel or Covenant ship and take part in big scale space battles against the infected ships of The Flood.
Drop in and defend your worlds on foot, collaborating with past enemies to push this parasite into extinction.
Whether by air, space, on foot or in vehicles, by the technology of Human and Alien weaponry, you have a chance. You can break the cycle, and stop the Flood once and for all.
Completely Freeform, and alternate take on the Halo storyline. Partly based on real Halo Back story.