A brief overview of the main story and characters in the universe of the highly acclaimed Halo games series.

Everything you need to know about Halo universe

A brief overview of the main story and characters in the universe of the highly acclaimed Halo games series.
This article is over 8 years old and may contain outdated information

The biggest exclusive for Xbox One is coming out on October 27, 2015 – Halo 5: Guardians. This is the fifth installment in the main series of the Halo games, which began its world domination in 2001. Throughout the years, the universe of Halo has been growing more and more, and it’s gotten to the point that if you’ve missed a game or two, it can be pretty hard to put all the pieces back together. Some people have never even played the previous installments, but do want to try Guardians out.

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The best case scenario would be to play through all the games in the beloved franchise and gain full personal insight into the story and the characters. But who has time for that? That’s why I’m giving you a brief analysis of the key concepts and events of the Halo universe.

After reading this guide, you will be ready for the events of the upcoming Halo 5 game. However, if you still plan on playing some of the previous games, be prepared for the spoilers. Now, let’s begin from the very basics.


The events of Halo take place in the twenty-sixth century. In this far future, mankind continues to explore near-Earth space and begins the process of colonization of other planets.

The first contact with extraterrestrial life forms happens in the year 2525, and the aliens turn out to be extremely hostile creatures. This event unleashes the main conflict, which involves the principal aggressor – the Covenant, a conglomerate of alien races. The only force capable of resisting the Covenant is a team of super-soldiers, known as the SPARTANs, which includes the protagonist of the series – Master Chief.

The Precursors and the Forerunners

First came the Precursors, then the Forerunners. These were the representatives of the ancient races that perished hundreds of thousands of years ago. There isn’t much information about the Precursors, except that they were the creators of all living things, including people. The Forerunners, on the other hand, have a much richer mythology. It is believed that the Forerunners were the ones who overthrew and almost completely destroyed their creators. According to one version, the creators personally acknowledged the Forerunners as a mistake, which eventually led to a riot.

“The Forerunners were a wise, highly intelligent, noble beings and with a belief in justice, in peace, they bravely faced the adversary. They sought to sterilize it.” – Cortana on the Forerunners

Whatever it was, the Forerunners became the strongest and most advanced race in the universe, who took the responsibility to protect other, weaker species.

The Flood (The Parasite)

“One single Flood spore can destroy a species.” – Rtas ‘Vadum, Halo 3.

It wasn’t a spontaneous natural phenomenon, although it was just as destructive. An invasion of parasites – Inferi redivivus, was the punishment afflicted on the Forerunners by those remaining few of their creators. The Forerunners had been fighting this plague for three hundred years, but the harder they tried to destroy it, the more parasites spawned from the spores, driven by only one instinct – to infect and devour everything that is sentient.

The Halos

The Forerunners had no choice, and they put all their efforts into creating biological weapons – the Halos (Halo Array, Sacred Rings). This weapon could destroy all of life within the galaxy – that was the only way out, destroying the only source of Flood’s nutrition.

“The only way to stop the Flood is to starve them to death.” – Cortana to John 117 and 343 Guilty Spark.

It’s interesting that the inner surface of the rings was suitable for life. With the help of terraforming, it became possible to create favorable conditions for the flora and fauna to further explore the impact of the Flood on different organisms.

Initially, eighteen rings with a diameter of 8,000 kilometers each were created on an installation facility called The Great Ark – the only place that was protected from the impact of the Halos. Subsequently, some Halos were destroyed or simply lost. However, the remaining seven were enough to put an end to the Flood, and unavoidably, to other life forms in the galaxy, as well.

“Halo doesn’t kill Flood. It kills their food. Humans, Covenant, whatever. We’re all equally edible. The only way to stop the Flood is to starve them to death. And that’s exactly what Halo is designed to do: wipe the galaxy clean of all sentient life.” – Cortana

After activating the Halos, the galaxy was seeded with life once again, and the remnants of the Flood disappeared for many years. This ends the history of the Forerunners and starts a new cycle.

The Covenant

Hundreds of thousands of years later, another group of beings boldly declared itself as the supreme one – the Covenant, a union of many races from different parts of the universe. Each species occupied a certain place within the empire, depending on its abilities.

With all its diversity, the Covenant, like many other nations, was united by one faith. The Forerunners disappeared, leaving almost no traces behind, except a couple of artifacts. Those few relics discovered by the Covenant made its people believe in its supremacy. Since then, they’ve been worshipping the Forerunners like gods, and thinking that Halos were the gates to immortality – the Great Journey, which, of course, was a big mistake.

“None will be left behind when our Great Journey begins! That is the Prophet’s age-old promise. And it shall be fulfilled!” – The Prophet of Regret

The Covenant, unlike the Forerunners, developed very slowly and produced most of its weapons and equipment in accordance with the “messages of the gods” and used their processing technology. Nevertheless, they managed to learn enough to be able to build spaceships, military transport, plasma beams, and chemical weapons.

The Conflict

During the search for the new artifacts, the Covenant had its first contact with people, and the subsequent war began. The next relic to be found on the human colonized planet Harvest clarified the true meaning behind the messages of the Forerunners, which said that their true heirs were humans and not the Covenant.

So, the Supreme Council of the Covenant had no choice but to declare humanity as heretics and start the war with them. This war would last for more than thirty years.

“At this point in time, the Covenant is at its most evil. They are hell-bent on the destruction of humanity, on scouring us from the universe.” – Graeme Devine, Lead Writer, formerly Lead Developer


Technologically, the Covenant was far ahead of humanity, so people had to create and improve their own weapon base. This war would have ended quickly enough if humans didn’t develop their first batch of super-soldiers – the SPARTANs, physically perfect and cybernetically modified fighters.

Dr. Catherine Halsey was considered the creator of the SPARTANs, including the training program and modification of MJOLNIR, the super advanced exoskeleton to which the SPARTANs owe most of their abilities. Subsequent generations of SPARTANs developed without the participation of Dr. Halsey.

“My SPARTANs are Humanity’s next step – our destiny as a species.”

– Catherine Halsey, describing the SPARTANs to an ONI interrogator

Initially, the SPARTANs headed peacekeeping missions, in particular missions to crush the rebellion against the unified government of the Earth. Fortunately or unfortunately, they had to deal with another kind of threat.

Master Chief

“He is neither the smartest, nor the fastest, nor the strongest of the Spartans. But he is the bravest, and quite possibly the luckiest. And in my opinion, he is the best.” – Dr. Catherine Halsey to Cortana

The most famous SPARTAN soldier is Master Chief, also known as John-117. Generally, super-soldiers don’t recognize the titles and choose one leader among their peers. However, the authority of Master Chief was so great that he was recognized as the Chief Petty Officer of all the SPARTANs.

The Covenant simply called him “Demon.” Due to his efforts, many of their attacks were repelled, the Halo rings were deactivated, and the truce was established. The Covenant subsequently collapsed and some of its members teamed up with humans. The rest of the defeated Covenant races formed the Covenant Remnant and continued to fight.


Before gaining popularity as an AI assistant in the new operating system from Microsoft, Cortana was an assistant to Master Chief. Dr. Halsey created Cortana for one of the first operations of the SPARTANs. They needed to hack the AI and gain data analysis. However, Cortana turned out to be much more than that.

In the Halo universe, in order to create an AI, a dead person’s brain was usually used. But in the case of Cortana, Dr. Halsey created a copy of her own brain. One day, studying the ins and outs of the SPARTANs’ training program, Cortana swore to defend the Master Chief at any cost – even if she couldn’t last longer than seven years, the life cycle of the normal AI.

“They let me pick. Did I ever tell you that? Choose whichever Spartan I wanted. You know me. I did my research. Watched as you became the soldier we needed you to be. Like the others, you were strong and swift and brave. A natural leader. But you had something they didn’t. Something no one saw, but me. Can you guess…? Luck.” -Cortana

The Prometheans

“They’re Forerunner robots. Hard light in battle armor. What can they offer us? Nothing but trouble, doctor. They’re simply killing machines.”

– SPARTAN Gabriel Thorne.

In Halo 4, we get to fight the new breed of enemies – the Prometheans. They once served as warrior-servants for the Forerunners. In order to avoid the destructive force of the Halos, they turned themselves into digital beings, thus being able to disintegrate into particles. Together with their lord Didact, they disappeared into the primary fortress world – Requiem.

After the defeat of Didact, the Prometheans joined the Covenant Remnant and its leader – Jul ‘Mdama. This, as well as the uncertain fate of Master Chief and Dr. Halsey, who was forced to join the Covenant, is where the story picks up in Halo 5: Guardians.

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Serhii Patskan
Serhii is the Writer at GameSkinny. He's been writing for GameSkinny since 2015. Before that, he's been writing for various outlets and playing video games, which eventually turned into a passion. The video games that have contributed the most to his enthusiasm for writing about this industry are Magic: The Gathering, Dark Souls, and The Elder Scrolls V: Skyrim.