Official Story for Metroid Prime

.:THE CHOZO:.
The Chozo... Over millennia, this bird-like race of creatures made incredible technological and scientific leaps. Traveling at will through space, they built many marvels across the universe - technological wonders of unfathomable complexity and cities unmatched in beauty. They shared their knowledge freely with more primitive cultures and learned to care for and respect life in all its forms.

Even as their society reached its technological peak, however, the Chozo felt their spirituality wane. Their culture was steeped in prophecy and lore, and they foresaw the decline of the Chozo coinciding with the rise of evil. Horrified by the increasing violence in the universe, they began to withdraw into themselves, forgoing technology in favor of simplicity. Tallon IV was one of several refuges they built-a colony bereft of technology, built of natural materials and wedded to the land and its creatures.

The years passed, and in time a great meteor crashed into Tallon IV, sending a massive spume of matter into the atmosphere and impregnating the land with a cancerous element known as Phazon. This element immediately sank into the earth and water, poisoning life wherever it bloomed. Most plants and animals died, while others mutated into hideous forms.

The Chozo called upon all their knowledge and technology to control the power of the Phazon, but their efforts were doomed to fail. All they could do was build a temple over the crater at the impact site, separate the Phazon core, and seal it away. Believing that someday a savior would return to the planet, the Chozo left for an unknown destination, leaving nothing but engraved accounts of their time on Tallon IV.

.:THE SPACE PIRATES:.
The Space Pirates were interstellar nomads, technologically advanced in both space travel and weaponry. When they plundered the Metroid population on SR388, they recognized in them massive military and energy resource potential. They immediately invaded the nearby planet of Zebes, wiping out all life (including most of the indigenous Chozo) and building a massive network of research facilities below the planet's surface.

Deep below the surface of Zebes, the Space Pirates researched Metroids for many years, even as a young girl orphaned by their raid on the neighboring planet of K-2L was growing up among the Chozo. Trained as a warrior and infused with Chozo blood, Samus Aran donned a Chozo-made Power Suit and cut a swath through the Space Pirates' operation, destroying everything in her path, including the gargantuan mainstays of the Space Pirate army, Ridley and Kraid. She eventually made it to the core of their base, destroyed all the Metroids she saw, and seemingly blew up the Mother Brain.

But the Space Pirates were far from finished. They immediately split their survivors into two camps. One remained on Zebes to begin rebuilding their ravaged facility and resuscitating Mother Brain, Ridley, and Kraid. The second set out in search of a planet with powerful energy resources. They didn't search long before they discovered Tallon IV, which was still emanating huge pulses of energy from the Phazon contained beneath the Chozo temple. Entranced by the massive potential of the strange mutagen, they immediately moved in, retrofitting their laboratories, transporters, and life-support systems into the Chozo Ruins.

As the Space Pirates mined the Phazon and experimented with it, they found that its capacity to mutate was unlike anything they'd ever seen, and they promptly started combining it with indigenous lifeforms. They refined their operation; powering their machinery with thermal-powered engines sunk deep in the molten depths of Tallon IV, they drove deep mineshafts and mined more and more Phazon, shipping it to their two main labs in the Phendrana Drifts, where sub-zero temperatures made specimen containment safer. Research leaped forward: by harnessing Phazon's power, they were able to create untold horrors that soon patrolled the dark caverns below Tallon IV's crust.

The Space Pirates also transported many species to their orbiting ship for zero-G Phazon experiments, unaware that Samus Aran had finally tracked their ship to its low orbit. As they continued with their unnatural experiments, Samus sped toward Tallon IV, preparing to wipe them out once and for all...