All Warhammer 40,000: Space Marine 2 factions explained – Imperial, Chaos & Xenos

Don’t know your Ultramarines from your Thousand Sons? You’re not alone, here’s a breakdown of all the factions you’ll need to know about in Space Marine 2.

Space Marine 2 is set in the vast Warhammer 40K universe with many competing factions. Not even all of the Space Marines are on the same side. Of course, those familiar with Games Workshop’s flagship franchise may already know the difference between the Loyalist and Chaos Space Marines, as well as all the Xenos factions like the Tyranids.

But for newcomers, it can be a bit confusing. So below, we’ll give you a breakdown of who’s who in 40K and which factions we’re likely to see in the game. To do this we’ll also give a summary of the lore to get you up to speed.

Who are the Space Marines?

The Space Marines (or Adeptus Astartes) are genetically enhanced super soldiers who make up the vanguard of humanity’s forces. There were originally twenty legions of Space Marines, but today these have been split up into hundreds of smaller chapters, each with their own distinct culture and methods.

This was to prevent any one chapter from becoming too powerful after a vicious civil war known as the Horus Heresy saw half the Space Marine legions rebel against the Imperium of Man and align themselves with Chaos, a malevolent force from a mirror dimension known as the Warp. The Chaos Space Marines would be defeated by the loyalists, but their forces still exist in the galaxy.

Each Space Marine legion was founded by a Primarch “son” of the Emporer of Mankind who used his own genetic code – and many suspect some Chaos sorcery – to craft his demigod children. In the current era of 40K, and after a ten-thousand-year coma, two loyalist Primarchs have returned to the setting. First, it was Roboute Guilliman of the Ultramarines, and later, Lion El Johnson of the Dark Angels.

Guilliman now rules the Imperium in the Emporer’s stead as his regent, commanding his blue Ultramarines to defend humanity from the swarming Tyranids, while The Lion hunts Chaos, far away from Earth (or Terra). The Emperor himself was gravely wounded by the traitor Primarch leader Horus during the Heresy and now sits on a vast life support system known as the Golden Throne. From here, he psychically protects humanity from Chaos. He uses his vast power to shine his light into space to aid his people across the cosmos.

Most of humanity worships The Emperor as a god. However, the Space Marines shun this religion, preferring to believe that he is just an incredibly powerful psyker who draws his powers from the Warp, even though that dimension has become overrun by Chaos and is ruled by its four gods.

Space Marine 2 sees various chapters make an appearance with the Ultramarines as the ones we follow in the campaign. However, in multiplayer, we can play as numerous Loyalist chapters as well as some Chaos Space Marine legions. In the campaign, we step into the shoes of Titus, a member of the Ultramarines who used to guard Guilliman while the Primarch slept. After battling Orks in Space Marine 1, Titus is facing penance for decisions he made during that game.

Who are the Chaos Space Marines?

The Chaos Space Marines are former loyalists who fell to Chaos when their Primarchs betrayed the Emperor and rebelled against the Imperium. Tragically, many of them were misled and manipulated into their treachery by the malevolent gods of Chaos who essentially feed on human suffering.

After the Horus Heresy, the traitor legions were chased into a terrifying part of space known as the Eye of Terror, somewhere where the Warp and realspace meet, so the influence of Chaos is strong. The surviving traitor Primarchs dedicated themselves to the Chaos gods and ascended to become powerful immortal beings called daemon princes.

Some continue to lead their legions and battle the Imperium to this day, while others have been content to stay in the Eye of Terror, safe from Imperial retribution. The Chaos forces sometimes unite under Abaddon the Despoiler, a former captain of Horus who’s taken over his legion and supplanted the daemon Primarchs as Warmaster of Chaos.

Abbadon has since led thirteen Black Crusades against the Imperium, each one strategically designed to weaken the Emperor’s grip and spread the influence of Chaos. However, his antics may have led to the return of the loyalist Primarchs and have also attracted the ire of various Xenos races who are becoming increasingly sick of Chaos, such as the Eldar, Necons, and Tau Empire.

Other Imperial factions

The Space Marines aren’t the only ones heading into battle against the Tyranids. The Imperium of Man is made up of various other allied forces:

The Inquisition

The shadowy human enforcers of the Imperium are greatly feared by nearly everyone. Split into three branches each committed to hunting traitors, daemons, and aliens, the Inquisition is relentless and radical, often sending assassins or entire armies after those they see as a threat to humanity – or their own power.

The Deathwatch

Technically, the Deathwatch is a Space Marine chapter but they operate differently from the rest. They’re under the command of the Inquisition and are comprised of Space Marines from many chapters who have been instructed to serve penance for a mistake, or various other reasons.

They’re essentially used as trouble-shooters (literally) for the Inquisition and are often sent to undertake shady tasks most Space Marines wouldn’t normally carry out. It’s seen as both a great honor and a mark of shame to have served with the Deathwatch, depending on the circumstances.

At the start of Space Marine 2, Titus is serving within the chapter after the events of the first game.

The Imperial Guard

The Imperial Guard (or Astra Miliatarum or just “Guard”) are the regular, non-enhanced, human foot soldiers of the Imperium who often fight alongside the Space Marines. Like most of humanity, they worship the Emperor and see the Space Marines as his “angels”.

Where there is only a finite amount of Space Marines, there are billions of Imperial Guardsmen and women across the galaxy, each defending their assigned planet or supporting the Space Marines on their campaigns. They also have an affinity for tanks and use them in great numbers.

The Mechanicum

You’ll see lots of little robotic guys in red robes in Space Marine 2, this is the cult of the Mechanicum who often fight alongside Space Marines and help them with their gear. Separated from Terra for thousands of years by Warp storms, the Mechanicum originated on Mars where its people became obsessed with technology and started worshiping it in the form of the Machine God / Omnissiah.

They would eventually join the Imperium, giving the Emperor access to their tech after he manipulated them into believing that he was their god made flesh. However, there is some truth to this lie. The real Machine God is likely a Ctan that escaped the Necron’s purge and was imprisoned beneath Mars by the Emperor. Over the centuries, its whispers shaped the planet and its people.

Xenos

Xenos in 40K simply refers to any alien race that didn’t originate on Terra (Earth). The Imperium is openly hostile to all forms of Xenos, mainly due to suffering at their hands when the first space-faring human empire fell into ruin.

However, since the return of Robute Guilliman, the first seeds of cooperation between humanity and some Xenos civilizations have begun to sprout. This is mainly because the Tyranids and Chaos have proved themselves to be the galaxy’s gravest threats.

The Tyranids

The main antagonists of Space Marine 2, the Tyranids may look like mindless dino-bugs, but they’re actually a sentient race of aliens who are determined to consume all biological life in the universe and use their biomass to make more Tyranids. They are controlled by a godlike Hive Mind from another galaxy who became aware of humanity due to the carnage of the Horus Heresy. It then instructed its bioforms to make the ten-thousand-year journey across the void to consume our galaxy.

The Tyranids are immune to the taint of Chaos and do not discriminate when it comes to food. Biomass is biomass. The race has been beaten back by the Imperium (and other Xenos) on three earlier occasions, but in Space Marine 2, the Ultramarines are fighting the fourth Tyranic War against an invasion named Hive Fleet Leviathan. This invasion is rampaging across the galaxy, consuming Imperial, Chaos, and Xenos worlds alike.

The Eldar

Also known as the Aeladari, the Eldar are essentially space elves and are an ancient race who ruled the galaxy before the rise of humanity. Their empire was so vast that it even eclipsed humanity’s realm before both empires fell into decline. The Eldar became hedonistic and complacent which led to the birth of the Chaos god, Slannesh, who went on to consume the souls of 90% of their species, driving the race close to extinction.

Today, they work to defeat Chaos, survive the aggression of the Imperium, and atone for their mistakes. They’re also wary of their old enemies, the Necrons, and are committed to purging the Tyranid threat from the galaxy. A faction of Eldar known as the Ynnari has united many of their worlds under one banner and has even formed an uneasy truce with the Imperium in the face of their shared enemies.

Not only did the Ynnari help the Imperial survivors of Abaddon’s Thirteenth Black Crusade get to safety, but they were also instrumental in the return of the Ultramarine’s Primarch Robute Guilliman – meaning that the Space Marines owe them a favor. There’s also a separate faction called the Drukhari, or Dark Eldar who are so vicious that they often make Chaos look tame by comparison.

The Necrons

A race that is even older than the Eldar who once went to war with the very creators of the Aeldari. The Necrons were once a militaristic but dying species who had a grudge against the godlike Old Ones (who created the Eldar, Humanity, and the Orks) for not helping them overcome their short and painful lifespans. They were then manipulated by another set of powerful beings known as the Ctan, who also had issues with the Old Ones, and then used the Necrons as footsoldiers in their war against them.

The Ctan essentially wanted to eat the worlds under the Old One’s protection and took advantage of the Necon’s plight. The Necrons were forced to turn their biological bodies into living metal skeletons and this is the robotic form they’ve been in ever since. This has caused them to envy organic life and covet what it represents.

After defeating the Old Ones, the Necrons turned on their Ctan masters and enslaved their evil gods. Rather than fighting the Eldar Empire at the peak of its power, the Necrons went into stasis for millions of years, hoping to reclaim the galaxy when they woke up. Billions of Necrons went to sleep dreaming of a better tomorrow.

Instead, they’ve woken up to a galaxy ravaged by war and destruction. Today, the Necrons fight to reclaim what they’ve lost and long to return to being creatures of flesh and blood. While they have no love for humanity or the Eldar, they have a special hatred for Chaos and the Tyranids so work to undermine them the most.

The Tau Empire

Dedicated to what they call “The Greater Good” the Tau species has allied with various alien races under one empire and seeks to protect its citizens and expand its borders. Many human worlds have also flocked to the Tau Empire for a better life – which has resulted in violent reprisals from the Imperium.

After the Space Marines fought the more technologically advanced Tau to a stalemate, both empires grudgingly agreed to a ceasefire. They also both recognized that there were greater threats than each other. However, the Tau continues to expand across the galaxy, causing problems for the Imperium when they encroach into their territory.

The Tau has since discovered that there are far worse things in the galaxy than humans as Orks, the Dark Eldar, the Tyranids and the thirsting gods of Chaos turn their attention to the fledgling empire. They’ve established a cordial relationship with the Eldar and a mixed one with the Necrons.

The Orks

Always chasing the next scrap, the Orks are a brutish and warlike race who were created by the Old Ones to fight the Necrons and Ctan. Without their masters to control them, the Orks have devolved into the creatures they are today, where all they want to do is wage endless war.

Luckily for them, in the grim darkness of the far future, there is only war. The Orks were the main antagonists of the first Space Marine game but since the emergence of the Tyranids of Hive Fleet Leviathan, they have fallen lower on the Imperium’s list of priorities. This may be something the Space Marines live to regret.

Not every faction listed above may show up in Space Marine 2, but it pays to know who all the movers and shakers are in the Warhammer 40K universe. And who knows who’ll show up in the DLC?