Plot

Super-soldier John-117, Master Chief of the United Nations Space Command, must battle a genocidal alien race known as the Covenant following his violent crash-landing on Halo, an ancient and mysterious ring-world.

You Play the mysterious John, known as Spartan-117 and The Master Chief, a Master Cheif Petty Officer in the United Nations Space Corp of the 26th Century. You are the last of a genetically enhanced group of super-soldiers of the Spartan II project. As the last of these super soldiers you alone wear The Mjolnir enhanced suit that increases your physical prowess through motor assistance. You are hastily removed from a Cryogenic freezer one day to find that the ship you have been traveling through space on, the Pillar of Autumn, is under attack from the Covenant (A conglomerate of several species of extra-terrestrials who have declared war on the Human race after their first inter-galactic settlement was formed) and you have been summoned by the Captain. Upon reaching the office you accept a pistol and an AI program, and are tasked with the protection of the AI because it knows the location of Earth. After battling through the ship and leaving in an escape pod you land on a mysterious ring world. After many days on the ring world you find that the planet is infested with another species of alien and must set upon a mammoth task to destroy the planet to protect the galaxy.—Gavin H

Mankind is being destroyed by a conglomerate of alien races all under the flag of the Covenant. A human spaceship is under attack and has no chance to survive, and now the only hope for mankind is for the Spartan-II forged Master Chief to make sure the Covenant do not get a hold of the ship's AI, and thus discovering the location of Earth. But the survivors of the ship are stranded on a strange alien planet called Halo, and everything is stacked against them. It becomes a desperate battle as the brave crew, lead by the Master Chief and the AI Cortana, try to survive the Covenant's assault.—Miriani

You are Master Chief, John, SPARTAN-117. You are the most efficient piece of military equipment designed. When you are defending the planet Reach, a training ground for other SPARTANS and marines just as you trained there, the Covenant, a race of creatures that are aliens to Earth, whose first message sent to the human race was "It is our gods' will to destroy you", overwhelm the planet's defenses and "glass" the planet(use all their fire-power to destroy whatever is left of the planet). You are on the Pillar of Autumn, one of the smaller ships of the UNSC forces that left Reach. It makes a blind jump into slipspace (and warp that forces the ship into an alternate reality, allowing it to go to places faster using coordinates) where you find the massive ring structure,Halo, looming before the Pillar of Autumn. The Covenant (who followed the Pillar of Autumn through slipspace) use all their power to destroy the Pillar of Autumn. You are forced to leave the ship and take a life pod to the only place that may actually be safe, the ring... You continue to venture the ring with whatever UNSC forces survive the devastating crash landing of the life pods. You discover the horrifying secret of why Halo is there and how to escape the ring world. But the Covenant are cunning and more advanced, and they never give up, not even if it means sacrificing themselves...—mikeythehalomaster

In the 26th century, humanity draws the wrath of a conglomerate of alien races. This "Covenant" is intent on exterminating the human race, which they view as a religious affront. Still an fledgling interstellar race, humanity is constantly pushed back by the overwhelming numbers and furor of the Covenant. The only thing keeping the human race fighting is the fact that the Covenant do not know the location of Earth. Instead all operations are carried out from the planet Reach. Ships in danger of capture are required to self-destruct or make "blind" hyperspace jumps away from Earth. The humans do have a few tricks up their sleeves, though. The best is the SPARTAN-II program, designed to forge elite soldiers through genetic modification. A plan is launched to use the SPARTAN-II soldiers to infiltrate a Covenant ship and discover the location of the alien homeworld. But the plan fails, and the SPARTAN-II soldiers return to Reach for cybernetic modification to attempt the plan again. But the Covenant are just as devious, and launch a surprise attack on Reach, destroying many of the human fleet ships. Only the Pillar of Autumn manages to escape, making a blind jump away from Earth in the hope that the Covenant will follow and not search Reach for the location of Earth. The plan works, but the Covenant make it to the jump point before the Pillar of Autumn, and launch another attack. In desperation, Captain Keyes orders the "Hushed Coffin" unsealed, and the last surviving SPARTAN-II soldier, known only by his rank of Master Chief, is awakened from cryogenic stasis. His orders are to protect the Pillar of Autumn's AI construct, Cortana, from capture, so that the Covenant can't retrieve Earth's location from it. The Pillar of Autumn is abandoned, and the Master Chief and the surviving crew members find themselves stranded on an artificial ringworld, Halo. Faced with superior numbers and a seemingly inexhaustible alien fleet, the survivors must make their final stand on this ancient alien world. But Halo hides a secret, The Flood, a weapon so powerful it could destroy the galaxy. Can the Master Chief overcome impossible odds and stop both the Covenant and the Flood? Humanity's fate rests in the hands of one genetically modified cybernetic soldier.—Anonymous