SKYNET used many different unorthodox tactics during the War, more so in the first and last stages of the engagement than at any other time.  The first stage of the War was one where mankind was slowly recovering from the massive nuclear strikes and SKYNET was just starting to extend its control over the initial territories that it would come to hold for most of the War.  During this phase, mankind was nearly beaten, the small groups of survivors were isolated, and SKYNET had a tremendous advantage if it could just get its production facilities established.  SKYNET felt that it could afford the luxury of playing with the few survivors, of doing long term testing of machine types while it built up its infrastructure.  The sudden appearance of the Resistance was almost as shocking as the realization that such an organized human institution would have taken years to develop and coordinate, years that SKYNET was unaware of its existence.

The last stages of the War saw a desperate SKYNET resorting to untried, often ad-hoc designs, stop-gap measures and odd strategies to defeat what had become a relentless adversary intent on SKYNET's destruction.  Two of those ad-hoc designs were the T500-R "Reaver" series and the T600-G "Gaunt."  Both units were designed for psychological warfare, to instill terror and uncertainty among the ranks of the scattered Resistance units.  SKYNET reasoned that if it could instill enough uncertainty or fear into the human survivors that it would have a ripple effect and would slow the spread of the Resistance.

Desperation often breeds innovation, and the psychological warfare projects of SKYNET were innovative to say the least.  Human test subjects were used extensively in the development of these two units and their reactions were gauged accordingly throughout all aspects of unit performance.  Production tests of the 600R series would often include using live test subjects in a controlled environment, pitting single or multiple test subjects directly against the 600R series.  Often, SKYNET would either allow direct observation of the field test by the other test subjects or would feed live video into their holding cells, often increasing the volume accordingly.  Fear was a carefully measured aspect of each test subject, their brain waves could be monitored passively, as could their vital signs; heart rate, respiration, blood pressure, brain waves, electrical output of the body as a whole, etc.  SKYNET found that both the T600 and the T500-R series were very effective in creating fear and panic among test subjects, and this fear often spread.  New test subjects introduced into the holding cells quickly adopted the same fear shown by test subjects that had been there for days before hand.  Sometimes, as test subjects shared information about what they had observed, other test subjects were observed to go into various states of either hyper activity or a lesser level of activity bordering on catatonia.  Neither state, SKYNET observed, was conducive to effective combat operations.

SKYNET soon found that specific frequencies of ultra-sonic sound waves mixed with specific electromagnetic field variations could directly affect the human mind and nervous system in a detrimental yet not-fatal way.  Projecting high powered broadcasts from an omni-directional sending unit caused test subjects to become more frightened, to experience larger instances of panic, and to become less effective in combat.  Certain frequencies of sound waves could cause panic and fear in the test subjects and these frequencies were carefully studied.  The nearer the test subject was to the broadcast generator, the more profound the effect was on the test subject.  SKYNET even experimented with directional senders, able to broadcast this wave form in a linear cone, a test which met with a high degree of success.  Stimulation of live subjects by the field effect produced remarkable results, from a direct observed reduction in aggression, to an inability to act, to the fine body hairs being charged and forced to stand on end, especially along the face, arms, and back of the neck of test subjects.  When this effect was matched to digital sampling of test subjects previously terminated or in the process of being terminated, with the volume and sampling matched to the wave effect perfectly, the overall result was quite profound.

Abject terror and involuntary paralysis of the human nervous system, voiding of bladder and bowels, hydrostatic lock of muscle groups, and a major decrease in the effectiveness of combat tactics.  Thus SKYNET had produced what the Resistance would eventually call a 'fear field generator' or FFG as it colloquially became known.  The FFG, like the later biological and chemical compounds produced by the renegade AI, were just a few of the weapons that the Resistance could not turn around and use on the Machines.    This generator was somewhat bulky, and linear due to the magnetic wave form acceleration coil packs required to modulate the EM frequencies at the specific levels required to produce the desired effect.  SKYNET's attempts to integrate the FFG into an existing unit proved unsuccessful as the modifications required to mount the unit often created severe structural compromises that were unacceptable.

SKYNET then approached the design problem from the opposite angle and built a unit around the FFG, rather than trying to integrate the FFG into an existing unit.  The result was the T600-G series, which was known as the "Gaunt" by Resistance forces, named for its long, willowy form.  The "Gaunt" lived up to its name sake.  At over three meters height (ten feet) and nearly a metric ton in displacement, the T600-G was tall and had an emancipated look to the design.  The arms and legs were long and waspish, the torso was narrow and tapered, with the FFG running coaxial to the main spinal brace.  Two high output hydrogen power cells were installed in the central torso, one to each side of the FFG, to handle the power requirements of the unit.  These were located in armored berths, behind plate armored hardened covers and were only accessible through the rear of the chassis.  From the front, the Gaunt was protected by better than three centimeters of case hardened hyperalloy that was durabonded and cold-rolled to form a lightweight but vacuous cradle for the internal components.

The FFG was controlled by two dedicated microprocessor arrays.  Directional broadcast units were installed in each arm, near the wrist of the unit, a wide spread array was installed to the rear of the torso, and the coil flash-over reducers actually exited the armored torso, running along the exterior of the spinal array.  When the FFG was operating, these coil flash reducers would prevent static buildup along the FFG array, a side effect was that each CFOR tended to glow a deep cobalt blue while in operation, a side effect of the energy being produced and broadcast.  Two CFORs were also mounted along the cranial module, running from the rear at the base of the attachment point up, around the top, and almost touching in the front.

The total visual aspect of the T600-G was carefully tailored to instill as much passive fear as possible.  The normally polished surface was dulled through industrial etching and a matte dark gray finish was molecularly bonded to the outer armor layer giving it a very worn, very old look.

The arms of the unit were composed of two, 1.5 meter long segments of hydraulic and servo ram assisted housing.  Free rotational joints were used, giving the T600-G an incredible amount of motion throughout the entire range of movement.  The hands and digital manipulators of the Gaunt were also exaggerated, lengthened into the surreal imitation of nightmarishly long fingers, and each finger ended in a twenty centimeter long serrated hyperalloy blade that could punch through steel armor plating or cut through anything less in one servo powered swipe.

The legs of the unit were likewise exaggerated, long and lean, giving a T600-G at full speed a very easily recognized gait and step as well as superior ground clearance.  Balance was also a consideration in the construction of the foot modules, which were four toed claws that could be used for striking as well as grabbing and manipulating.  The T600-G could even scale vertical walls by driving its claws and toe claws into the building material and climbing by strength alone, a tactic found out too late by many Resistance units.   

The reflexes of the T600-G were pushed to design limits, giving it above average speed, strength, and reaction time, all carefully controlled through a dedicated microprocessor array that worked independently of the main processor array.  Sensors were the same as the T600-S variant, as was the ability to sample, edit, and broadcast sound, the processor and broadcast unit which would later be reproduced and installed on the T600-R series units.  The T600-G's cranial module was also sculpted, to form a very death-like visage designed to inspire fear through visual acuity alone and the ocular arrays were deeper set, given a very skull-like semblance. 

Records indicate that at least three of the field test units were sent out with specially tailored black, tattered ballistic nylon fiber optically adaptive camouflage cowls, more akin to “Ghillie Suits” than to a cloak, to further enhance the psychological effect.  This last item proved to be key in spreading fear among the survivors in the ruins, of a tall shape, shrouded in tattered black cloth, which hunted among the wreckage and rubble.  These "Dark Angels" as some called them, came to be feared greatly among the dim witted and the superstitious.  A fact that was not lost to SKYNET and its psych-warfare development.  The optically adaptive camouflage cowls allowed the T600-G to draw in upon itself, wrap itself in the cloak while hiding in the shadows.  The material of the cloak was a passive modulator which tried to adapt and blend each cell of its construction to the color of the surroundings, a process which often took about forty-five seconds to accomplish.  While the T600-G was powered down, with its cloak pulled over and hunched up in the shadows, it was almost impossible to detect visually, let alone by electronic means.

The T600-G was also a master of ambush, able to construct improvised snares and traps from the rubble around it as well as employ other camouflaged means of both escaping detection and of dispatching targets of opportunity.  On at least four occasions, T600-G units were known to hide in partially collapsed basements or under light debris, pouncing out to attack at the last possible instant.  Another favorite tactic was to hang upside down by its toe claw mounts, coiled up upon its chassis while passively scanning for targets.  When an unsuspecting human walked underneath, the "Gaunt" would rapidly power up, reach down, and physically acquire the target, rending and tearing it to pieces as it lifted it off the ground.  Such brutal target destruction was often the key to inspiring fear in the human survivors, and SKYNET programmed the T600-Gs to take advantage of all types of macabre data from man's collective history.  Heads were mounted on top of piles of rubble, words were written on the walls of ruins using the severed limbs of targets, and many bodies were discovered that had been mutilated in horrendous ways.  When the T600-G was set to autonomous mode, and learning enabled, some units began to display unique personality traits, such as the collecting of trophies (heads, hands, teeth, etc.).  Not all of these trophies were taken after the target was terminated, some were taken prior to termination or as part of the termination process.  Corpses featuring severed limbs, neat amputations, or partial to complete decapitations were often found in the ruins during the day in very visible sites or along known human paths of travel.  The T600-G series ruled the night for many years, and up until the Final Victory, there were still some rear echelon support areas reporting T600-G like activity.

The 500R series was a direct engagement unit, but the 600-G series was more clandestine.  While the 500-R ruthlessly pursued any human it detected, it did so with a feral outlook.  The 600 series was much more methodical in the completion of its missions, being a true hunter which could not only judge its targets but also pick them with care.  History will show that of all the many various types of designs that SKYNET fielded, it was probably the 600-G which earned the nomenclature of “assassin” machine.