What if...
You all know the story. Spartan-117, ranked as a Master Chief, singlehandedly fights half of the war to save the galaxy against the Covenant of alien races that sought to exterminate all life in the galaxy through the use of the technology of an extinct, but almost incomprehensibly advanced, civilization, known generally as the Forerunners. Fighting against impossible odds, he beats back their attacks, outnumbered and outgunned at every turn but always inexplicably able to prevail.
pause
You all know the story. Samus Aran, bounty hunter and part-alien by blood, continuously foils the intentions of the Zebesian race, an insectoid alien species that prided itself on its love for space piracy, through the use of warrior training and an incredibly sophisticated suit of powered armor developed by a nearly extinct, but almost incomprehensibly advanced, civilization known as the Chozo. Fighting against impossible odds-
pause
I'm sorry... you don't really know the story. Not all of it. At least... not in the way you think. There were Spartans, and there was a Covenant, there was a Samus Aran, and the Space Pirates. The Chozo and the Forerunners both exist, so to speak. For what it's worth, I'll just tell you outright: they're one and the same. Didn't see it coming? Think about it. You know the Varia Suit Samus Aran wears? Class 10 combat skin. The Power Suit alone ranks at Class 6. The MJOLNIR armor of the Spartans is perhaps Class 2, if that.
Still taken aback? Xel'Naga. Protheans. Ancients. Alimbics. While they may not have been the same species (not even my own ilk are sure), it is almost certain that all the great ancestral races of the galaxy are, if not the same, then related. My own theory is that they were, themselves, of a covenant, one which expanded far and wide across the universe, seeding knowledge and technological advancements wherever they roamed. Another similarity? The Zerg. The Reapers. The X-Parasite. The Flood. Many of these races yielded a parasitic, murderous (even if only by necessity) engineered organism, synthetic or organic, or were threatened by those that came before. They disappeared when the organisms became uncontrollable. Said parasites went dormant, until something caused them to arise and begin their frenzies once more.
But enough of that. I'm simply here to let you know that bits and pieces of the stories you know as "Halo" and "Metroid", among others, are true. How can they be true at all, if they are fiction? Each are, in fact, pieces of the same puzzle, the same story told to different groups who then proceeded to make their own... erm, dramatizations of what they perceived truth to be. Your dimension saw these stories as little more than that, an exciting but ultimately fictional fabrication designed solely for the purpose of your entertainment.
And who am I, you ask? I am simply a narrator. The Narrator, if you wish to get all definite (as is your society's standard). I am the narrator for a world that could have been, that was, that may yet be, or may even exist as the true reality, where this world in which you listen to my words is the fiction. Wouldn't that be quite a change? Ah, but I am not here to bring existential crises to you, my friends, oh no. I only wish to tell a tale, a tale of humanity's endeavor amongst the stars, of a war-seeking Covenant of aliens which made peace with humanity, only to form a Galactic Federation to combat a murderous race of Space Pirates in the then-distant future.
"Spartans" and the Chozo-trained are now both parts of the same elite combat force – the Guardians. Imagine, if you will, a Spartan, physically perfect – more than perfect, by human standards – mixed with the grace and agility of those gifted with Chozo training (for a chosen/compatible few, infused with the blood of the Chozo to become even more adept), and equipped with armors far more powerful than the MJOLNIR system ever was. Such are the Guardians. Dangerous, even when unarmed and unarmored; apocalyptic, when fully equipped for combat.
What could stand in the way of such an unmovable force? The juggernaut of the Space Pirates' Phazon research. I know you've seen rough approximations of Phazon's mutagenic effect through your simple entertainment systems; the real-life effects, however, are unpleasant. Brutally so. Even the Guardians are little match for such bastardizations of nature. The Galactic Federation contributes Sangheili warriors, fierce and on a physical par with Spartans without ANY alterations, and battle-hardened, rock-steady Turian soldiers to hold the line of battle; but they only serve to stem the flow from the leaks that the Guardians are forced to ignore in favor of the bigger picture. Earth, still the cradle of human civilization, teeters on the edge of Armageddon, protected only by a mixed bag of genetic supersoldiers and teenaged walking weapons. Oh, I neglected to mention that there are active Guardians who are but children. The fact sometimes slips my mind, age being relative to me.
This is their story. This is the story of a battle against all that would stand between humanity and its survival. Remember that you haven't escaped this fate, yet, yourselves. If you could, would you fight for your species' survival?