Blue Energy

This page describes an interpretation of the effects of the mysterious and dangerous blue energy, a reoccurring element commonly seen within some of the enemies. The following information is purely conjecture, based largely on in-game observation and fan speculation.

Blue Energy

At some point, zombies may begin to see special transformations to their physiology beyond regular zombiism. One prominent form of such transformation has a distinct blue color radiating from the body of the infected in one form or another. It's assumed that these specific transformations are the results of strong energy exposure, a consequence of the introduction of the plague.

Several zombies affected by blue energy will develop remarkable abilities that generally make them more difficult to deal with than the average undead. The powers, strengths, and the extent as to how much energy has altered them physically can greatly vary.

Zombie	Description
Charged Zombie	Charged Zombie appears to be a Dark Skeleton, sharing a very similar appearance. Over time, energy exposure has caused it to develop a bright blue nervous system that glows all over his face, arms, and upper body. Its chest glows particularly brightly. It has the ability to transmit large, inhuman amounts of energy to charge its entire body. Doing so allows it to run at an incredibly fast speed that proves fatal when colliding with something (for both itself and any units unfortunate to get in its way). When this happens, it begins to make a distinct electrical noise and flashes strongly for a few seconds until its glow is fully maintained.
Demon	Demon is a large infected with notable blue spikes all over his upper body. It's likely that energy exposure has caused him to grow into a hulking zombie capable of producing crystal-like protrusions. These spikes can expand and retract, suggesting they're not entirely solid yet capable of maintaining a certain form when not currently in use. Thanks to his transformation, Demon can use these spikes for a devastating special attack where he slams both fists into the ground, sending energy through his arms, and causing it to travel underneath the surface. From there, the energy quickly erupts out from the ground as spikes that can attack units and objects. After performing this move, he can quickly recover lost energy as the spikes on his body which shortened after performing his special attack grow back near instantly afterward. This may suggest that the spikes also act as excess energy reserves. When killed, a light blue liquid expels out from his body as it breaks apart into pieces.
Necromancer	Necromancer appears to be a regular Zombie. However, his arms, face, and upper body glow bright blue. His chest has a veiny pattern that glows as well. His eyes are solid blue as opposed to the usual yellow and small, floating blue particles emanate from his body. One of the most interesting aspects of Necromancer is his ability to float in midair. Although it isn't clear how he stays afloat, the existence of Energy Sphere, a gelatinous gooey orb and the only other enemy encountered that can float, could explain how Necromancer managed to gain this ability as its existence would mean it would be possible for particular zombies to be able to float with enough exposure to energy sources. Apart from levitation, he can also spawn enemies from the ground through massive energy discharges, causing Dark Skeletons beneath the ground to suddenly rise.
Psy	Psy appears to be an infected scientist. Considering the size of his head and the glowing blue veins on it, it can be assumed that energy exposure has manifested primarily in his brain, his head growing unnaturally large as a result. This also shows when Psy's whole head and eyes begin to glow as he performs his unique psi attack. This interesting ability allows him to send out psionic shockwave blasts capable of rippling the air around him. It is likely that he converts the energy within his head into a vibration that he can expel with a force strong enough to push certain threats away as a sort of defense mechanism. Interestingly, Psy appears to be screaming as his mouth opens wide when performing this attack. However, it could simply just be an involuntary reflex as a result of its peculiar attack. When killed, a light blue liquid expels out from his body as it breaks apart into pieces.
Small Insectoid	Small Insectoid is an infected that shares its name from Insectoid. While sharing virtually no similarities with its normal-sized counterpart, this may hint that both these creatures likely came from the same infected: Offal. While Insectoid does share more physical similarities to Offal, it might be possible that Offals can transform into Small Insectoid, given that they both do share a similar body frame size. From its appearance, it's likely that it was an Offal that's been primarily exposed to blue energy, causing it to remain the same size but grow both gray and bright blue flesh, similar to the other blue enemies encountered in stage 7. Its eyes are now a brightly glowing blue. Lastly, it grew out two new appendages from its back, although they only flail around uselessly when it runs around. When killed, a light blue liquid expels out from its body as it breaks apart into pieces.
Putrid	Putrid appears to be a fusion of an unknown number of infected, creating a large, abominable mass of living flesh indiscriminately covered with multiple limbs. Its appearance suggests blue energy was a direct cause of this mutation rather than exposure as shown from its exterior comprising of large, round bulges of flesh partially connected by pulsating energy patches. Putrid is likely the result of a large group of infected individuals coming into direct contact with a source of blue energy, causing their combined flesh to fuse together and eventually reshaping itself into a single large infected. While Putrid can detect enemies and move around sufficiently enough, it's unclear if its unnerving transformation has turned it into a hive-minded zombie that works together or not. While structurally sound, for the most part, it will explode when killed, suggesting that the bulges of flesh are under some tension and have a build-up of internal pressure. Interestingly, it will also release a group of three Rottens. Considering their appearance, they may have been regular Zombies that were originally a part of the large group of infected that would eventually become Putrid. However, they went unused during its creation process and were instead relegated to being stored within the bulges of flesh, slowly rotting away as a result. It is possible, however, that some of the limbs sticking out of Putrid could belong to some of those Rottens.
Energy Sphere	Energy Sphere is a floating blue ball of a gelatinous substance. As evident by its name, it is alluded to be blue energy and more specifically, an entity made purely of it. An unusual ability that it possesses is the ability to float in the air. It also appears to be sentient or at the very least aware of human presence as it actively seeks out to infect those that approach it, and speeding up when detecting one that is very close to it. A successful charge into a unit will turn them into Offal.
Blue	Blue appears to be a regular Zombie. However, some of his flesh has turned gray but much more of it has turned bright blue. Considering the extent of his transformation, it could be assumed he has have been exposed to blue energy for quite some time. As a result, he has become bioluminescent (to the point that his eyes behave like blinking lights) and has gained the ability to deliver a stunning attack. This new form has also given him natural fire resistance. When killed, he ceases to glow.
Blue Runner	Blue Runner appears to be a regular Fast Zombie. However, some of his flesh has turned gray but much more of it has turned bright blue. He likely shares the same background as Blue.
Big Blue	Big Blue appears very similar to the above two enemies, having some of his flesh turned gray and much more of it bright blue. However, he is noticeably bulkier body in size, roughly similar to Cop, and a few short appendages have begun to grow around his upper body. Considering the extent of his transformation, it could be assumed he has have been exposed to blue energy for quite some time. As a result, he has become bioluminescent (to the point that his eyes behave like blinking lights) and has gained the ability to deliver a stunning attack. This new form has also given him natural fire resistance. Additionally, he also gained a rather fascinating ability to heal himself. Despite this, it seems Big Blue is incapable of healing large wounds as evident by the large cavity on his stomach which doesn't seem to be repairable.
Warthog	Warthog appears similar to Blue, the most notable similarity being the torn black pants with the two torn areas showing the bioluminescent blue skin. However, yellow pustules, blue energy mounds, and brown growths have grown outwards all over its upper body. Given the extent of its horrible mutation, it has likely been exposed to a particularly strong source of blue energy for quite some time. This devastating transformation has resulted in it becoming much more difficult to kill but at the cost of some of its other strengths, although It still retained its previous fire resistance. Since it is still mobile, it's speculated that it must first find a suitable spot before it collapses in on itself and make the final step towards transforming into Egg, its final form.
SWAT (Zombie)	SWAT is an infected dressed in protective attire very similar to that of the TMF squad. As all TMF members do not turn after death, it would seem unlikely for SWAT to be a former squad member. However, it could be possible that some members were infected directly by energy itself as shown by the bit of pulsing energy that is visible on the side of SWAT's face. As strong sources of blue energy have been shown to completely turn infection-resistant units, the main example of this in-game being Energy Sphere, it is very likely that some amount of it was the cause of their unlikely transformation. While it did not manage to turn him into an Offal, it was successful in transforming into a tough zombie that also turned developed fire resistance. This transformation has caused it to swell up in several places, predominantly his head and arms. Yellow pustules have begun growing on the side of his head.
Locust	Locust is an infected convict. As a result of strong energy exposure, two mounds have grown on Locust. A small one sticks to its head and a much bigger one with several blue insect-like limbs and a tail is attached to its back, constantly forcing Locust to bend forward whenever he stands up. His own arms have become more insect-like as well. While the mound on his head is practically ornamental, the one on his back is multifunctional. Due to his transformation, he moves around on all fours, hopping off the floor with the help of his new limbs to stabilize him. The blue limbs also serve as Locust's main form of attack rather than using his own ones.
Prisoner	Prisoner is an infected convict. As a result of strong energy exposure, several lumps have grown out of its head and lower back near its waistline. These lumps pulsate and most are covered in blue energy as well. Prisoner is host to Small Insectoid, which it becomes after being killed. It's unclear how exactly Small Insectoid is a part of Prisoner, whether it was created from within it internally or if Small Insectoid used Prisoner as a bodysuit in for protection.