If you've never played any of the Halo games, or don't have a good understanding of the core history and events which shape the game's fictional universe, this article will help get you up to speed. This Newbie Guide will bring you up to speed on the essential information you'll need to understand what the game is about.
What is Halo about? A Brief History Lesson.
Halo is a military sci-fi epic centred on humanity’s struggle to survive against powerful alien civilisations and ancient, god-like technology left behind by a long-extinct race called the Forerunners. At its heart, Halo explores themes of sacrifice, faith vs. truth, artificial intelligence, and extinction-level warfare.
Taking place in the 26th century (2500s), Humanity is ruled by a unified government. Prior to the events of the first game, conflict between Humanity and the alien race known as The Covenant begins in the year 2525, on the Human colonised planet known as Harvest. At this time, Humanity had expanded their reach across the galaxy unopposed by any meaningful hostile intelligent alien life and the planet of Harvest was lightly defended. Out of nowhere, The Covenant arrived on Harvest investigating Forerunner relics they believed were hidden away on the planet and made first contact with the Human race. This inevitably led to conflict, and The Covenant ordered the extermination of the Human race - labelling them an abomination.
Fast forward to the year 2552, after nearly 27 years of conflict with The Covenant, Humanity is on its last legs. Outmatched by Covenant technology, Humanity is now simply trying to avoid extinction. This brings us to Reach - Humanity's second most important world next to Earth. Reach contains major shipyards, research labs, military command outposts and is the formal headquarters of the UNSC SPARTAN program. Reach is ambushed by an enormous fleet of Covenant ships and invaders, taking Reach by surprise.
Despite a valiant effort by Noble Team, a Spartan detachment led by Carter-A259, which included Spartans Kat-B320, Jun-A266, Emile-A239, and Jorge-052 - all members regretfully perish in their effort to ensure Humanity has a chance to survive. Thankfully they succeed in all their objectives and manage to deliver the experimental new A.I. Cortana to the UNSC Pillar of Autumn before the planet is glassed by the Covenant. This leads into the beginning of the first game, Halo: Combat Evolved, which is where Spartan 117, the Master Chief is introduced and paired with Cortana.
The UNSC warship Pillar of Autumn, carrying Master Chief and the A.I. Cortana, emerges from a blind slip-space jump and discovers a massive ring-shaped alien structure: Halo. Pursued by Covenant forces, the ship crash-lands on the ring, scattering its crew across the surface. At first, Halo appears to be an ancient weapon the Covenant believe will grant divine salvation.
As the conflict escalates, Master Chief uncovers the ring’s true purpose. Halo is not a sanctuary or ascension device — it is a galactic superweapon designed by the Forerunners. Its function is to eradicate all sentient life capable of sustaining the Flood, a parasitic organism discovered imprisoned within Halo’s facilities.
The Flood rapidly escapes containment, transforming the conflict from a war between species into a fight for survival against total extinction.
With the help of the monitor 343 Guilty Spark, Master Chief learns that activating Halo would destroy the Flood — but only by killing every thinking being in the galaxy, including humanity itself. The Covenant’s religious crusade is revealed to be based on a lie.
Rather than activate the ring, Master Chief chooses to destroy it. He infiltrates the wreckage of the Pillar of Autumn and overloads its engines, triggering a catastrophic explosion that shatters Halo before it can be fired. Master Chief escapes with Cortana, leaving the Flood temporarily contained and the Covenant’s holy objective denied.
Why did the Covenant attack Humanity?
The Covenant are after Forerunner relics and artefacts. Humanity pose a great threat to this pursuit because the ancient Forerunners had deemed the Human race as "Reclaimers", which made Humans biologically compatible with and able to interact with Forerunner technology. Humans were the chosen successors to the Forerunners, not The Covenant. If the alien races which make up the Covenant realised this truth, it would completely dismantle their entire religion. As a result, The Prophets deem Humanity an abomination and order a total genocide of their species. At the same time, they rewrite their own religious doctrine to justify the extermination so their followers don't question or oppose their directives.
Halo Factions
The UNSC
The UNSC stands for United Nations Space Command and acts as Humanity's military and exploratory arm. The UNSC protects Humanity from any and all threats. They also explore and exploit new technologies, discovered by investigating alien worlds and artefacts. They are Humanity’s unified military and governing force, struggling to survive extinction through adaptability, sacrifice, and advanced supersoldiers.
The Spartans
Spartans are genetically enhanced human warriors engineered to fight impossible wars, serving as humanity’s most powerful symbol of hope.
The Covenant
The Covenant are a vast alien theocratic empire waging genocidal war in the name of a false religious journey built on ancient lies.
The Forerunners
An extinct, god-like civilisation whose failed attempt to preserve life reshaped the galaxy through weapons of mass extinction.
Sentinels
Automated Forerunner machines tasked with enforcing ancient protocols and containing threats without understanding morality.
Monitors
A.I. overseers created by the Forerunners to maintain installations and carry out catastrophic orders with perfect obedience.
The Banished
A brutal, post-Covenant war faction driven by power and survival rather than faith, born from the collapse of religious empire.
Understanding the Forerunners
The Forerunners were an ancient, galaxy-spanning civilisation that existed over 100,000 years before modern Halo events, possessing technology so advanced they were mistaken for gods by later species.
They believed themselves chosen as caretakers of all life, a philosophy known as the Mantle of Responsibility, which guided every aspect of their culture, law, and warfare.
At the core of Forerunner mythology is the Mantle: the belief that the most advanced species has a sacred duty to protect lesser civilisations and maintain balance throughout the galaxy.
Long before modern humanity, ancient humans were a technologically advanced interstellar power and rivals to the Forerunners. Believing humanity posed a threat to the Mantle, the Forerunners defeated and devolved humans to a primitive state and rewrote galactic history to erase this truth.
The Flood was their downfall
The Forerunners’ greatest failure was their war against the Flood. Despite their god-like technology, The Flood adapted to everything and entire Forerunner worlds fell. As desperation grew, the Forerunners accepted the fact they could not win. As a final solution, the Forerunners built the Halo rings, the Ark and shield worlds with preservation systems.
The Halo Array would kill all sentient life in the galaxy and as a result, starve the Flood into dormancy. The Halo would also preserve life via indexed genetic archives for later reseeding.
They sacrificed themselves
When the Halo Array was activated the Forerunners knowingly wiped themselves out and the galaxy was rendered silent. Life was later restored without memory of what came before and the Forerunners became a myth and their works were mistaken for divine relics.
A handful of Forerunners survived temporarily however, but as digital consciousness and AI constructs known as Monitors. These remnants maintained the galaxy according to ancient rules, long after their creators were gone.
Humanity would be their successors
The Forerunners ultimately chose humanity as their successors. They designated mankind as Reclaimers and made their technology compatible with human biology.
How the Halo Series differs from the Games
The Halo TV series significantly diverged from the game mythology by re-imagining established lore to fit a character-driven television format rather than a mystery-driven epic. It introduced non-canonical elements such as a human raised by the Covenant, removed the sense of mythic distance around Master Chief by frequently unmasking him, altered the Spartan program’s emotional framing, and re-framed Forerunner technology as something activated by select individuals rather than humanity at large.
Now you should have a better understanding of the core mythologies, themes and ideas explored throughout the Halo universe, with respect to the games and how it differs from the Halo TV series.
