Their biology are similar to a human's as their bones are structured normally to a regular human, the Harran Virus will alter their biology when the sun goes down. At night, the once weak infected turn into deadly hunters with their motor coordination and sensory capabilities being increased, capable of running much faster and move more freely around the environment unlike being sluggish and tedius during day. They are also extremely vulnerable to UV light at night as they drain their abilities and weaken them, effectively burning and stunning the infected ones.
- Biter: The regular infected and have notable degradation of their bodies resulting in major loss of movement, speed and coordination. They attack by flailing their arms around and feeding as well as occasionally using weapons. They are mostly dangerous in groups where their slow speed is less of a disadvantage and are also fairly quiet at a distance and can be difficult to be spot in darker or noisier areas, but can be heard heavily breathing and moaning when up close.
- Viral: Humans that have only been recently succumbed to the infection and as a result, they retain the physical strength required for them to possess a high level of fitness and agility. They run faster than most infected and can also jump and climb buildings.
- Gas Tank: Humans originally part of the special cleanup unit sent into Harran however were killed and remain roaming throughout the city still in their hazmat suits. They are just as slow as Biters, however their red oxygen tanks on their backs that can be set off when hit. Their hazmat suits prevent them from biting but also makes them fireproof and can still attack with their fists.
- Goon: Large and strong infected that towers at roughly 8 feet tall, carrying heavy rebars which it uses to smash into the ground and swing at their targets. It can also use it's left arm to bat survivors away as a secondary attack. They are much stronger than regular infected, but are very slow moving and lack the ability to climb at all.
- Toad: Infected noted for it's ability to fire green acidic phlegm that age to the target with their attack in combination with the phlegm. Toads display more agility than some special infected, able to leap across rooftops with ease however are relatively weak.
- Demolisher: One of the largest infected types and it's strength lies in it's ability to break down walls and lift and toss vehicles across far distances. However, it is quite slow and can be easily avoided prior to it's charge. It is as unintelligent as Biters and it's attacks have longer windup compared to it's smaller kin, making them easier time dodging.
- Bomber: Infected that is noted for it's exposed organs and it's shambling jog. Bombers can pick up speed and will begin to convulse when non-infected humans are within it's proximity. The result of their fates will always end with their bodies exploding, blinding anyone with it's coagulated blood.
- Screamer: Infected children whose screams disorient a survivor's vision and renders them unable to fight as well as drawing in numerous other infected. They will also continuously take low but progressive amounts of damage if within it's screaming range.
- Volatile: Infected humans that only appear at night and are broad-shouldered, being slightly taller than Biters. They are full-bodie nude, showing exposed bones and muscle as well as a mandible jaw. They are extremely fast and can scale obstacles and buildings with a special pounce attack that can be fatal.
- Bolter: Infected that are noted for being the only infected ones that don't attack any survivors, instead fleeing in their sight. They have green lumps covering their bodies that glow and one of the few infected that only appear at night.
- Night Walker: Special types of Biters that only appear at night and are ordinary Biters that have undergone a rapid and sudden transformation. They become much more aggressive and will attack faster with more damage.
- Night Hunter: Player-controlled predators that watch over nests of incubating Volatiles and have superhuman abilities which offer an edge over survivors in the quarantine. Night Hunters can howl to reveal survivors globally and their tendrils allow them to traverse at extreme speeds with their primary attack being to pounce. They can spit different projectiles with the first one being used to attract infected, second that disables all UV lights, third that disables their survivor sense and the fourth is shooting a toxic puddle.