Think Dead Space is just about healthy doses of limb removal? Think again. There's actually quite a bit to know about the horror series' universe, especially if you're just jumping in for the first time or are in need of a refresher.

Sure, you might know what a Necromorph is--but do you know where they come from? Do you know how the Church of Unitology came to be? And what about this weird Marker thing everyone keeps babbling on about (right before committing suicide)? We'll explain it all. Beware, though: There are spoilers beyond this point.

Right now, the world's population is 7 billion strong and growing, and humanity wages war over resources all the time. Fast forward a few hundred years, and one could speculate--barring any world-crushing catastrophes--that poor Earth would be completely stripped of anything remotely useful. That means no more video game consoles, no more 300" HHHHHHHD TVs, no more iPhone 252s, and a lot of super bored humans, who are all strangers to the ancient practice of "playing outside."

Something--anything--had to be done to save mankind from the everyday monotony of recording audio logs and text logs (which were, for some reason, always written in all caps). Someone had to step in, to make things right. The Concordance Extraction Corporation answered the call.

CEC, a prominent company in the deep space mining biz, came up with a way to harvest previously untapped resources by building giant spaceships called planet crackers. These may sound like giant Saltine treats, but they're essentially Death Stars. The planet-cracking process took about three years to complete, and it basically consisted of the aforementioned ships exploding entire worlds into giant chunks, then refining those chunks into useful...stuff.

Thanks to CEC's small fleet of planet cracker-class ships--with the USG Ishimura being the first and most famous--mankind was restored to greatness, and people could finally buy iPads again. The world (and all of Earth's space colonies) rejoiced.

During one of its planet cracking expeditions, the USG Ishimura sent out a distress signal just before all communications with the vessel were severed. Unwilling to lose its most iconic (and expensive) spaceship, CEC deployed a crew to investigate. One member of the crew was series protagonist Isaac Clarke, an engineer, who signed up for the mission because his girlfriend Nicole worked on the Ishimura.

But once Isaac and company landed on the giant ship, they found it deserted--odd, considering it was home to dozens of CEC staff members. The only clues they could find regarding the whereabouts of said staff members were in the form of the blood stains that coated the floors of the Ishimura's lobby. HMMMMM...

That's when Isaac and his group were besieged by horrific monsters with knives for hands. With only his trusty Plasma Cutter--the hacksaw of the future--at his side, Isaac dismembered his way through the murderous hordes of creatures, all the while being harassed by hallucinations of Nicole. Who, it turned out, was totally, 100-percent dead.

Later, Isaac discovered that the USG Ishimura's true objective during its latest planet cracking excursion wasn't to harvest resources, but to recover a strange alien obelisk--called the "Red Marker"--and bring it back to Earth. Realizing how horrible of an idea this is, Isaac destroyed the Marker and escaped into space via shuttle. But what exactly was that Marker thing? Well, to understand that, we have to rewind time a bit...

In the year 2214, a scientist named Michael Altman and his team of science friends were busy researching an asteroid impact crater off the Yucatán Peninsula. There, they eventually discovered a strange alien artifact buried deep in the crater's center in the Gulf of Mexico.

At first, everyone was super pumped about the discovery, and they built an underwater facility to house and study the artifact--dubbed the Black Marker--in between congratulatory high fives. For a while, people were all like "omg can you believe we found this cool, twisty-shaped rock thing?" Alas, their celebrations were cut short, as they quickly discovered that the Marker was bad news. Why? Because...

The Marker emitted an ultra high-range frequency, which basically drove everyone nuts. At the very least, they'd experience a concerning range of nasty side effects, including hallucinations and the desire to perform ritualistic suicide. Obviously, this was problematic for the people studying the thing.

But what was more problematic was the effect of the Marker's signal on the dead. It reanimated the cells of organic tissue, contorting and twisting the muscles and bones of the deceased to form horrific creatures with a penchant for bloodshed. Those monsters are called Necromorphs, and though there are many variations, most of them look like zombie versions of Edward Scissorhands. What's more, they're all but immune to bullets. The only way to put them down for good is to dismember them, limb by limb.

So, Necromorphs were running around the Black Marker research facility, murdering everyone in incredibly imaginative ways, and Altman decided that wasn't a good thing. Also, he was surprisingly immune to the insanity-inducing effects of the Marker, which the crazies who were still alive interpreted to mean that he was some sort of prophet to which the artifact spoke. We'll get to this in a bit.

After many a close call, Altman survived insurmountable odds and successfully blew up and destroyed the underwater facility--and, supposedly, the Black Marker along with it. Pretty much everyone was pissed about this, including the Earth's Government (uncreatively named EarthGov), which funded the research, as well as the crazy fanatics who believed the Marker to be a sign from God.

Right as the whole Marker ordeal came to an end, poor Altman was captured by two government employees. These guy had gone off the deep end, fully believing Altman to be a religious icon--so they murdered him, billed him as a martyr, and used his death as a catalyst to form the Church of Unitology.

Fast-forward 200 years later (when Dead Space takes place), and Unitology had become a widely practiced religion. Its leaders proclaimed that humans were the creations of intelligent alien design, and that the Marker was the Holy Grail that would grant religious followers eternal unity. Which it did--except, you know, in Necromorph form. We know what you're thinking: "How could Isaac fight against murderous monsters when he's just an everyday space engineer?" Well, funny you should ask.

Well, more accurately, he was equipped with Resource Integration Gear (RIG for short), which kind of made him look like a bizarre robot/human hybrid. RIGs were utilized by much of humanity's adult population in Dead Space's lore, as they made for great health monitoring systems (as indicated by the color of the spine-mounted display) and strength augmenters.

Even the most basic of RIGs contained holographic projectors on the wrist, which acted as a GPS device for directing the user to a set path of coordinates. More complicated RIGs, which were often equipped to the heavy-duty suits of service workers (like Isaac), had modules installed to allow for the use of Kinesis and Stasis. What are those? Well...

Stasis modules basically let humans shoot globs of energy(?) out of their hands, which drastically slowed the movement of anything it touched. It was designed for use in hazardous occupations (boring), but Isaac found it useful for slowing down the aliens that were trying to kill him.

Kinesis, on the other hand, let him pick junk up by shooting Force Lightning out of his fingertips--which would be awesome for magically summoning console controllers to the couch without moving. Instead, mankind chose to use Kineses for dumb things, like moving humongous rocks and turning door handles without actually touching them (which, on second thought, is actually really cool).

Okay, so remember how Altman blew the hell out of the underwater research facility and destroyed the Black Marker? Well, before he did that, he had uncovered a sort of "genetic code" for the artifact, which EarthGov got a hold of after his involuntary martyrdom.

That means the government was able to figure out a way to artificially create new Markers based on the genetic blueprints of the original--and the first duplicate had been sent to the faraway planet of Aegis VII (the planet the Ishimura retrieved the Red Marker from) to be studied from a safe distance. Bummer that didn't work out so well, eh?

While drifting through space in a mere shuttle, Isaac activated a distress beacon and was ultimately saved. THEN he was handed over to EarthGov and placed in an insane asylum on the Sprawl, a giant space station/colony. This was done partially because he'd gone a bit wacko after having had so much contact with a Marker, but mainly because EarthGov wanted to probe his brain for Marker secrets.

After three years of being force fed memory-erasing meds and having his brain violated, Isaac suddenly "regained consciousness" during a Necromorph outbreak, which had overrun the entire colony. And that could mean only one thing...

Where did it come from? And how did it get there? Well, it was all Isaac's fault, actually. His close encounter with the Marker on the Ishimura meant his brain had been forcefully ingrained with the blueprints for building more of them. And since EarthGov had been shoving needles into his mind to find those blueprints, they were able to figure out how to construct as many of the things as they pleased.

Isaac knew he needed to destroy this new Marker, and dismembered the limbs of Necromorph-ed men, women, and children--f*&# those things--by the hundreds in order to complete his mission. Along the way, he encountered even more hallucinations of his dead girlfriend Nicole, and witnessed all sorts of creepy drawings (most in blood) by Unitologists, proclaiming that the Marker would make them all "whole."

What is Convergence? Well, it was never really explained in either Dead Space 1 or 2. But! It sounded really bad. What we do know is that it was triggered when a ton of Necromorphs gathered around a Marker, at which point they all started to get sucked up into the air.

Not one to wait around and see what would happen should Convergence occur, Isaac figured out how to destroy the Marker (and succeeded in doing so) to prevent Convergence. His actions were surely heroic--but he couldn't have done all that without a little bit of help.

Why is this important? Well, mainly because Ellie plays a large role in Dead Space 3. During his lovely, totally kill-free travels through the Sprawl, Isaac teamed up with this CEC pilot in hopes of putting an end to the Marker-produced madness.

Ellie sacrificed a lot to help him out--namely one of her eyes, which was slowly and painfully removed via screwdriver by a crazy dude on the Sprawl. But the fact is, Isaac couldn't have completed his selfless objective without her, as she not only provided assistance throughout Dead Space 2, but also saved his ass at the end (and became his new love interest). Then, right after the credits finish rolling, a mysterious voice piped up over a transmission. And guess what it said?

EarthGov constructed not one, but many new Markers based on the blueprints stored in Isaac's brain. You'd think mankind's best and brightest would've figured out pretty quickly that the Marker's aren't so much sources of energy as they are instruments of extinction, but hey, POLITICS, RITE?

We know Dead Space 3 will at least partially take place on the frozen ice planet of Tau Volantis, which is supposedly the Marker homeworld. What will Isaac find there? And how will the addition of two player co-op and weapon crafting affect the tension of the series? Find out in our Dead Space 3 review, which goes live this Tuesday at midnight.

Think Necromorphs are scary? Then check out the Top 7 uncomfortably sexy video game animals, or what would happen if Duke Nukem had failed his mission.