Quick note, I just wrote this because I was bored. I started writing and this is what I ended up with. You can interpret it how you want, or simply just read it. I hope you enjoy.
The darkened sky and the blistered earth, they were both permanent reminders of what mankind had done to itself. The war had been nearly two hundred years ago, but still the scars remained, still the earth suffered for what they had done. A bird hadn't been seen soaring the skies for centuries, nor that of a deer, or even a forest for that matter. The atmosphere was beginning to die, there were no longer any trees to produce oxygen, or any technology for them to leave the planet. So now mankind was just waiting for the day until the earth would forsake them, much like what they had done to it.
Great oceans had been turned to sand, and desserts to glass. Any rain that fell from the sky was acidic and burned anything that touched it. How humanity had managed to stay alive for this long was a miracle. Most of mankind had started living underground, where they could find water, and the rain could not reach them. However, there were those that clung to the ideals of days long since passed. They had built towns, and even cities among the ruins of old ones passed. People would not let themselves die, they kick and fight the whole way, certain that they would still escape.
But there would be no escape for the population that was left, there would be no escape for the prisoners that had destroyed the prison that was once a beautiful earth. The day was getting closer, and everyone knew it, for the clouds grew thicker, and the small portion of wildlife that remained grew thinner. They told themselves that they would still survive, that a miracle would happen and they would be saved. But they were wrong, for it wasn't a miracle that would happen, but something much worse.
Their planet would be saved, but they would nearly be hunted to extinction, and there would be nothing that they could do about it. For a great evil would take the place of the trees, and pools of their own blood would refill the destroyed oceans. The world would be born anew, but with owner much more fearsome then the last, for these owners were as unforgiving as death, were as deadly as the bombs that had fallen already, but these owners would none the less insure the survival of the planet. But as the planet would survive, mankind would die, like a flickering candle blown out by the wind.
The true owners of the planet came like a storm, coming in faster than anyone would believe. They had appeared seemingly overnight, but they had made their presence well known by the next day. They killed, not for power or money, but for survival. Not just survival for themselves, but also what mankind had nearly destroyed. For with them came the power to repopulate the world, to let the dying breeds of animals to flourish once more, to find but a single tree and watch it become a massive forest.
Cities would be replaced, not by the new owners of the planet, but by nature, which had been destroyed to create the towering cities. Oceans would yet again run blue, and so too would the clouds clear from the skies, showing the sun. The sun would no longer be denied access to the earth, it would once more heat the surface and bring life to the plants and trees that so needed it. The struggle between power would be short and brutal, and surely all humans left on the surface would be destroyed. There would not be even one human allowed to live, for though they seemed brutal, the Xenomorphs would cleanse a filthy world, before taking the reins themselves.
The Xenomorphs were not the scourge of death that the humans believed them to be, but were instead creatures that upheld the balance of life and death. They would kill for their survival, and the survival of creatures and planets alike. For when the bombs fell, the Xenomorphs were freed, the humans had lost their hold over them and would never regain it again. The Xenomorphs would repay the humans tenfold for what they had done. And they would not stop at earth, they would travel the galaxy, and so too the universe afterwards, until the true plague that was mankind was erased.
And with these notions, began a bloody war, the humans not even knowing the wrongs they had committed. But still they tore down forests, and mined away planets, all for their own personal gain. It was never technology that the universe needed to survive, but instead a simple hunter, that would not give up on the life it could see around it. As the humans fell, there was yet another Xenomorph for every one dead, and through the sheer number of Xenomorphs mankind was pushed to the verge of extinction.
But at the very edge of death, the Xenomorphs granted them one last chance, to redeem themselves before the entire species would be wiped out. And mankind lived without the aid of technology for years after, building walls of stone to protect themselves from the harshness of nature. And cut only the trees needed for houses. The Xenomorphs had protected the balance of life, and now watched the humans start anew, watching for the fatal slip that technology would bring with it. And so the Xenomorphs slept, they slept for years to recover from the battles they had fought, their scars almost able to heal.
Until once more they were called to the front lines, but this time mankind was prepared, and they were not so easily pushed back. They had advanced rapidly in the years that the Xenomorphs slept, and now the inmates were killing the jailors. And mankind would once more destroy what they had, but not before pushing the Xenomorphs to extinction, the only creatures that had ever tried to help them.
There will be no sequel or continuations on this, it's just a story explaining a fight that mankind was never supposed to win, and the consequences for defeating its most powerful enemy. I wrote this because it can be hard to continue on with the same story for a while, I'm just refreshing my writing here.
