Hazardous Environment Combat Unit

The Hazardous Environment Combat Unit (HECU) is a fictional United States military special forces unit prominently featured in the first-person shooter computer game Half-Life, and its expansion packs, Opposing Force, Blue Shift, and Decay. The Marines of the HECU are specially trained to deal with a variety of indoor combat situations, particularly involving a dangerous environment and unconventional enemies. The Marines are often referred to as "grunts" by fans of the game, and also as such by Black Ops operators in the game.

HECU in Half-Life
Following a catastrophic resonance cascade at the Black Mesa Research Facility, bizarre aliens from Xen teleport into the complex and begin attacking personnel. The Hazardous Environment Combat Unit is dispatched to the facility to fight the aliens and regain control of Black Mesa. Unknown to the surviving personnel at Black Mesa, though, the Marines have also been ordered to eliminate Black Mesa's civilian personnel to ensure that the incident is covered up. The HECU rapidly takes over the surface areas of Black Mesa and dispatch forces into the interior to eliminate the aliens, Black Mesa Security Force, and bring important members of the Science Team up to the surface for brutal interrogation.

The HECU's initial foray into Black Mesa is highly successful. The Marines quickly gain an advantage over the confused and frightened survivors and aliens and establish a substantial presence within the facility. Black Mesa's civilian personnel fail to put up any notable resistance, as many personnel mistakenly believe that the Marines are there to rescue them, and those who try to defend the facility against the HECU are outgunned and overwhelmingly outnumbered. In a matter of minutes, the HECU takes control of Black Mesa's central command areas and issues orders over the public address system for the facility's remaining personnel to surrender. The troops begin fortifying key surface areas with sandbags, mounted machine guns, and fixed artillery.

The tide soon turns against the HECU, though, as the Xen aliens teleport into Black Mesa in overwhelming numbers. Surviving facility personnel lend their help to Dr. Gordon Freeman, who is able to sneak and fight his way across the facility despite all the HECU's defences. Freeman quickly becomes a priority target of the troops. Their anger toward him is exemplified by the graffiti seen in the "On A Rail" chapter of the game, which reads "YORE DEAD FREEMAN" [sic] or "SURRENDER FREEMEN" [sic] and, in one instance, the train passes by a set of Trip Bombs with "DIE, FREEMEN" [sic] written near them. Also in the same chapter two soldiers who were guarding the area can be heard talking about Freeman and their proposed revenge. As the Xen aliens swarm through Black Mesa and a sinister team of "Black Ops" gains advantage over the military, the HECU, which is suffering appalling casualties, is evacuated as aerial bombardments tear into the facility. The evacuation is woefully incomplete, leaving many Marines behind in the facility, in the unenviable position of being caught amongst the forces of the Black Ops, the Xen aliens, and the newly-arrived Race X creatures.

HECU in Half-Life: Opposing Force


In the original Half-Life game, the Hazardous Environment Combat Unit was simply referred to as "the military" or "soldiers". In the expansion Opposing Force the protagonist, Corporal Adrian Shephard, is one of those men, and during the opening titles that display his personal info, his training is listed as "USMC Special Forces" and his current assignment is listed as the "Hazardous Environment Combat Unit, Santego Military Base, Arizona".

Opposing Force takes place several hours after the initial resonance cascade. The player's character, Adrian Shephard, is knocked unconscious when his Osprey transport is shot down by Xen forces, and wakes up several hours later in the Black Mesa Infirmary. Shephard regains consciousness just in time to witness the HECU begin to pull out all of its troops. However, he is prevented from leaving when the mysterious G-Man seals him in the facility. Shephard is forced to continue deeper into Black Mesa, where he encounters and takes charge of the remnants of HECU who have also been left behind during the evacuation. Shephard and his men find themselves combating not only the aliens from Xen, but also the newly arrived "Race X" aliens and a group of government Black Ops assassins who have recently been dispatched to the facility, who appear to have orders to eliminate any remaining HECU Marines as well as to destroy Black Mesa with a nuclear device.

The Hazardous Environment Combat Unit also appears to have access to more advanced military technology than their regular counterparts, as the Marines wear Powered Combat Vests (PCVs).

Furthermore, in both games, the troops are deployed in Osprey aircraft, which at the time of the game's production, had not yet gone beyond Engineering and Manufacturing Development (EMD) and low-rate production with the United States Marine Corps.

HECU weapons and equipment
The Hazardous Environment Combat Unit troops, while utilizing a variety of equipment and firearms, are all equipped similarly. Each soldier is equipped with an urban camouflage battle dress uniform and a Powered Combat Vest and can be equipped with a PASGT helmet and, depending on his specialisation, blowtorch or medical supplies.

Powered Combat Vest
The Powered Combat Vest (PCV) is a protective vest worn by the soldiers of the Hazardous Environment Combat Unit, over which the LC-2 Harness is worn. Part of the combat equipment used by the HECU in their initial incursion into Black Mesa and during the events that occur throughout Half-Life ' s storyline, the PCV is designed to protect the user from chemical, biological, radiological and physical threats during operations in the unit's defined battlespace. The vest increases the effectiveness and versality of the user, allowing them to operate in environments which are outside the normal bounds of the regular infantry.

The PCV is compatible with a gas mask resembling the M40 Field Protective Mask with built-in night vision goggles. In addition, the PCV includes a Geiger counter, morphine administrator (which allows the soldier to function normally even after serious injury), anti-toxin delivery system, tactical radio, and a head-up display (HUD) in the protective mask lens which tracks the user's medical condition and weapon ammunition. The vest contains an on-board computer system that constantly monitors the user's health and vital signs, and reacts to any changes in the user's condition.

Additionally, during the events seen in gameplay, the PCV provides complete protection to the centre mass of the user, protecting the torso, abdomen, shoulders, and back. This is provided by the electrically powered shield which stiffens the fibers of the suit to provide a hard, resilient layer of armor to absorb the kinetic energy. With a fully charged vest, the user can survive several dozen rounds of small arms fire or even a direct hit from a rocket propelled grenade. The PCV also provides protection from high level electrical and thermal energy, biological and chemical threats when sufficiently charged. The PCV can be charged by power modules either from the operational area or specially designed models which form part of the unit's arsenal.

It may be noted that the PCV is comparable to the HEV suit, which is worn by several Black Mesa personnel, including Gordon Freeman. This similarity is mostly attributed to the types of equipment included in both. In addition, the PCV's armour charge is also rechargeable at civilian, military or government electrical chargers, including those that are designed specifically for HEV suits. This has led to fans speculating that the PCV is either a precursor, or a derivative of the HEV. However, the PCV includes night vision goggles, as opposed to the HEV suit's flashlight.

While the Half-Life storyline suggests that both the PCV and HEV suit are separate pieces of equipment, the similarities between both may simply be the result of Opposing Force's programmers modifying the HEV suit's interface from Half-Life to that of a PCV for Opposing Force.

Detailed list of weaponry
The weapons utilized by the Hazardous Environment Combat Unit are based on several currently available weapons:


 * M9 pistol (Note: This weapon only appears if the High Definition Pack is installed; it replaces the Glock 17)
 * Glock 17 pistol (Note: This is replaced by the M9 when the High Definition Pack is installed).
 * IMI Desert Eagle with laser sight. The ammunition is indicated in the game as .357 caliber, but the magazine capacity is the same as the .50 caliber. (7 rounds)
 * MP5N with grenade launcher (Note: This is replaced by the M4A1 Carbine when the High Definition Pack is installed).
 * Franchi SPAS-12 shotgun
 * M4A1 Carbine with M203 grenade launcher (Note: This weapon only appears if the High Definition Pack is installed; it replaces the MP5)
 * M40A1 sniper rifle
 * FN M249 Squad Automatic Weapon
 * M2HB .50 caliber machine gun
 * Sentry minigun turrets
 * Manned rocket turrets
 * Mortars
 * Dual-mount M2HBs (in sandbag bunkers)
 * M23B laser tripmines
 * Autonomous sentry turrets

The HECU have also been observed to carry a rocket launcher in trucks that closely resembles the SMAW rocket launcher.

Vehicles

 * AH-64A Apache attack helicopter
 * V-22 Osprey V/STOL aircraft
 * M1A1 Abrams main battle tank
 * F-16 multi-role fighter
 * M44A2 2.5 Ton Truck
 * M2/M3 Bradley infantry fighting vehicle