What a Marker is and what it does. (Spoilers!)

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The Marker is a piece of alien technology from the hit action horror game series, Dead Space. A Marker is an alien device that acts as a sort of signal generator, similar to a radio tower. Markers were scattered across the galaxy by an unknown race of advanced beings. The reason is unclear, but the effect is evident. Markers produce vast amounts of endless energy, but this is only a minor trait.

As mentioned before, the Marker sends out a signal. Using electromagnetic waves, it affects the brains of different species in a variety of ways.

Recipients of the signal that possess a weaker mind experience it as a sort of high pitched whine. The sound takes hold, driving them insane. Effects include, but are not limited to, dementia, hallucinations, fits, seizures, and eventually, death (often by suicide). The afflicted often attack those surrounding them, regardless of their relation.

Recipients of the signal possessing a higher intellect, may see strings of numbers, symbols, and code. This is the Marker trying to communicate. The Marker sees those with a higher intellect as both a tool and a threat. It may try to conscript them, often speaking to them through visions. The visions can manifest as dreams, ghostly apparitions, or by automated writing through the subject. If the being possesses a malignant view of the Marker, it will often attempt to hinder them with dementia, paranoia, and suicidal tendencies.

All of this is extremely effective on its own, creating a very dangerous situation for any population. But it is nothing compared to what comes next.

While the signal alone can cause homicidal tendencies, it wouldn't be enough to consume a whole country in chaos, let alone a planet. For that, you'd need something capable of widespread devastation. Something much, much worse.

Once the panic spreads, and the death total begins to climb, only then does the true horror begin.

The signal takes dead cells and begins to bring it together, liquefying it into a fleshy goo. This substance begins to spread at a extremely fast rate, often over anything in its path. It is known as, "The Corruption."

Once the corruption comes into contact with larger masses of cells, like a corpse, it begins to transform it. The body is reshaped in the most horrendous of ways, varying between species and body type. These reformed bodies are turned into puppets of the Marker. Now designed to be the perfect killing machines, they hunt down any still living creature and slaughter it without mercy.

These puppets are known as "Necromorphs."

The longer the Marker signal is active, the more the corruption spreads, and the deadlier the necromorphs become. At a certain point, necromorphs can change dead and live bodies into more necromorphs themselves. These necromorphs are called infectors, spreading the pathogen through a special proboscis that is injected into a subjects brain.

The necromorph pathogen alters the cellular make-up of creatures at a terrifying rate. Bone and tissue is broken down so fast that blood boils. Extra limbs are created to enhance the necromorph's effectiveness. Different necromorphs can be created from different types of creatures and their physical state of being. For example, an average adult human would become what is known as a slasher, while an infant would result in the form of a lurker.

Once the signal has been active long enough, other necromorphs begin to emerge, compiled of multiple bodies, or special ones. A large group of people could fuse together to create something like a tripod, or a brute. A man missing one or both legs could become a leaper, while a very sickly person could become an exploder.

The goal of creating the necromorphs is to gather enough bodies to create a "Convergence Event." All the bodies and necromorphs are gathered at the Marker for the event to begin. The Marker sends out a shock-wave by releasing mass amounts of energy. The wave lifts all the bodies into the air and forms them into what is known as a brother moon by compressing the cells with that of a moon or asteroid nearby. The moon gains sentience and begins to communicate with other moons, seeking out new worlds to feed on. When a world is found, the cycle begins again, as more Markers are sent out by the moon.

So in short, the Marker is a very, very, very bad thing. If you want a more in depth explanation, or are just curious, I encourage you to read the Dead Space Wiki. It contains both interesting and accurate information regarding any questions you may have about the Dead Space universe. I also encourage you to experience the series yourself. Be warned though, it is not one for the faint of heart or stomach.