Disclaimer: I do not own Yugioh.
When the world was young, two unnamed forces contended for the dominion of the universe. One was pure white, and believed in the purity of the mind and body, seeking to share its wisdom among all. The other was dark, holding contempt and hatred as dark as itself for his counterpart, and sought to twist his partner's teachings into his own demented version. And as the two forces contended, mortals on Earth watched their encounters and in time, gave them names. The white one was named Good and the other was named Evil.
After countless of encounters and equal ties, the two forces decided that they will have one final showdown to settle the issue, and decided they that it will be a game of wit and skill. They chose Earth as their battleground, for the mortals on Earth known as man knew of their existence. Thus they traversed across stars, planets and lands until they came upon the ancient lands known as Egypt. And it was there did they began to take form.
For reasons unknown, Good splitted itself into two. One took the form of a serpent with scales decorating its red, almost endless body and two great wings and claws protruding from its front sides. It gave a frightening appearance with its two mouths, both filled sharp, glinting silver teeth. Its eyes glared yellow and the orb on its forehead glowed sapphire. With a mighty thrust of its wings, it launched itself into the sky and gave an earth-splitting roar which easily made the sun cower in fear.
The other took the form of what is known today as a griffin, a fabulous creature with the head and wings of an eagle and the body of a lion. Much like its brother, a sapphire orb glowed on his forehead as well. Combined with its shining gold body, it easily shamed the sun with its magnificence. As it finally to began to take form, it gave a loud roar, announcing its existence to the world. Taking its place beside its brother, they took home in the skies.
Evil, who wanted his own space, took home on the earth. Using a human as a reference, it shaped itself into its own version of a human. The result was terrifying to say the least. With spikes shooting out from its shoulders and crimson-red eyes, added with its dark blue and muscle-packed body, it gave a deadly appearance. Its forehead was stretched sideways with sharp spikes sticking out from them, forming a crown of sorts. It too had a sapphire orb on its forehead, though its glow was darker, almost black. As it heard the two roars in the distance, it reared its head and gave its response, challenging its counterparts' authority.
And the game began.
As both Good and Evil began spreading their influence, the people of Egypt came to fear and respect these new creatures and revered them as Gods. And they were named. The red serpent which dominated the sky was named Slifer the Sky Dragon, god of the underworld, for it was believed that its body was coated red with the blood of those who have died. The gold griffin was called The Winged Dragon of Ra, for its body shone with the light of Ra, the sun. And the last was named Obelisk the Tormenter, Lord of Destruction, for wherever it goes, destruction follows.
In time did the Gods learned that the humans possessed Ka, a soul that could be transformed into a monster given proper training. They too learned that the people of Egypt revered the pharaoh, believing that he was the son of God. Because the Gods needed a medium to give training to humans, decided they that they would make it true. And thus each God poured a portion of their knowledge and power into the unborn baby of Pharaoh Ramses, who was still in the wombs of his mother. When the baby was born it was evident that he was the son of Gods, for his hair had was of three colors- red, blue and gold- and he had eyes that shone crimson- a trait unseen before in the line of pharaohs. The baby was named Atemu.
As Atemu grew it became more evident that the power of the Gods was within him. At the minor age of two he mastered the Egyptian language- both in writing and speech. At the age of five, he was unbeaten and unbeatable in all games, earning him the title 'King of Games'. As he entered the world of politics at the age of eight, it took him only two hours before he had the entire court's ears and when he was brought to the battlefield at the age of nine, it was he who devised the strategy which brought the enemy to their knees. It was not until he ascended the throne when the Gods decided to intervene once more. By their own subtle means they taught him how to control Ka and summon his own soul monster. Then they manipulated him to spread the teaching through Egypt. It was not long before monsters became a common sight. These monsters were soon called Soul Monsters. And hell broke loose.
Although the methods of the Gods were subtle, they were not unnoticed by Pharaoh Atemu. Tired of being a pawn in their game the young pharaoh did research and finally found a way to challenge the Gods on equal grounds. Gathering his six high priests and priestess and, with their combined effort, he performed the Millennium Ritual and created the seven Millennium items- puzzle, ring, necklace, key, rod, eye and scales. Turning to his priests and priestesses, he said, "To each of you I will give a Millennium item. Guard it both with your body and your soul until I am ready." And guard it they did.
When it was his fourteenth birthday, he assembled his high priests and priestess once more and decided it was time. Using his sharp wit, he tricked the Gods into going to a new 'realm' he 'discovered'. Only when the Gods stepped into the Shadow Realm did they noticed something amiss. And they confronted young Atemu about it.
The young pharaoh merely said, "It is time." And the eye of Horus appeared on his forehead. Invoking the power of the Millennium Items, he challenged the Gods to a Shadow Game.
The Gods, who thought they were superior in both wit and skill, merely laughed in contempt as they accepted his challenge, unknowingly falling into his trap. And thus the Shadow Game began.
In terms of power, the Gods were indeed superior compared to Atemu. However the Shadow Games were more than just power alone. Besides that, the Gods were unversed in the rules of a Shadow Game and were soon easy plucking for Atemu. The game was not totally in the control of Atemu, however. Unused to invoking a Shadow Game, the young pharaoh was soon getting drained and started making costly mistakes. And the game ended in a tie.
As a final resort, the pharaoh leapt out of the Shadow Realm and sealed it along with the three Gods. Collapsing out of weariness, he prayed that the seal would remain there forever. However the High Priestess Isis, holder of the Millennium Necklace, informed him that it would not. "The seal would not remain forever my pharaoh. In order for it to become unbreakable it will have to be reinforced one more time." She told him her vision of the future and that he will have to plan how to reinforce the seal. And plan he did.
