Hazardous Environment Combat Unit

"I just overheard a secure access transmission: soldiers have arrived and they're coming to rescue us!"

- Black Mesa Scientist

The Hazardous Environment Combat Unit, often abbreviated as HECU, is a United States Marine Corps special forces unit featured prominently in Half-Life and its expansions.

Introduction
The soldiers of the HECU also known as The Hazardous Environment Combat Unit and are specially trained to deal with a variety of indoor combat situations, particularly involving a dangerous environment and unconventional enemies. Members of HECU are trained by drill instructors Dwight T. Barnes and Sharpe, and train at bases guarded and staffed by members of the Military Police. The Marines are often referred to as "grunts" by fans of the game, and also as such by Black Ops operators in the game.

They are featured in Half-Life, and its expansion packs, Opposing Force, Blue Shift, and Decay.

HECU in Half-Life
"I've killed twelve dumb ass scientists and not one of them fought back... This sucks."

- HECU Marine

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. Many soldiers disagreed with their orders, as said by a Marine: "I didn't sign on for this shit. Monsters sure, but civilians? Who ordered this operation, anyway?"

The HECU's initial foray into Black Mesa was highly successful. The Marines quickly gained an advantage over the confused and frightened survivors and aliens and established a substantial presence within the facility. Black Mesa's civilian personnel failed to put up any notable resistance, as many personnel mistakenly believed that the Marines were there to rescue them, and those who tried to defend the facility against the HECU were hopelessly outgunned and overwhelmingly outnumbered (as a Marine puts it, "I killed twelve dumbass scientists and not one of 'em fought back! This sucks."). The HECU soon took control of Black Mesa's central command areas and issued orders over the public address system for the facility's remaining personnel to cooperate and submit to interrogation. The troops began fortifying key surface areas with sandbags, mounted machine guns, and fixed artillery. Although there were few of them, there were also some snipers, one of which shot at and fatally wounded a security guard.

The tide soon turned against the HECU, though, as the Xen aliens continued teleporting into Black Mesa in overwhelming numbers. Surviving facility personnel lent their help to Dr. Gordon Freeman, who was able to sneak and fight his way across the facility despite all the HECU's defenses. Freeman quickly became a priority target of the troops. Their anger toward him was exemplified by several sets of graffiti seen in the "On A Rail" chapter of the game, which read "YORE DEAD FREEMAN" [sic], "SURRENDER FREEMEN" [sic], "DIE, FREEMEN" [sic], the latter of which is accompanied by 1 or 2 tripmines. Also in the same chapter two Marines can be heard talking about Freeman and their proposed revenge for killing so many of their friends. The full conversation is as follows:
 * "So, who is this guy, Freeman?"
 * "They say he was at Ground Zero."
 * "Science Team? You think he was responsible, sabotage, maybe?"
 * "Yeah, maybe. All I know for sure is he's been killing my buddies."
 * "Oh yeah, he'll pay. He will definitely pay."

As the battle raged on, the Xen aliens began to gain the advantage and the HECU, which was sustaining appalling casualties, was evacuated as aerial bombardments tore into the facility. The evacuation was woefully incomplete, however, leaving many Marines behind in the facility (in blatant violation of the policy never to leave another Marine behind) 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 Marine 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.

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


 * Glock 17
 * M9 Beretta
 * .357 Desert Eagle with laser sight. The ammunition is indicated in the game as .357 Magnum, but the magazine capacity is the same as the .50 caliber - 7 rounds.
 * MP-5 Submachine gun with attached grenade launcher.
 * M4A1 Carbine with attached grenade launcher.
 * SPAS-12 Shotgun
 * M40A1 sniper rifle
 * M249 Squad Automatic Weapon
 * Laser-guided missile launcher
 * M2HB .50 caliber machine gun
 * Autonomous Sentry Turrets
 * M202A1 Rocket turrets
 * Mortars
 * Laser Tripmines

Vehicles

 * AH-64A Apache attack helicopter (Note: The Apache is primarily used by the US Army. The USMC uses the Bell AH-1 SuperCobra as their attack helicopter)
 * V-22 Osprey V/STOL aircraft
 * M1A1 Abrams main battle tank
 * M2A3 Bradley infantry fighting vehicle
 * F-16 Multi-role fighter (Note: The USMC does not operate any F-16 fighters. At the time of the games production, the primary attack aircraft was the Harrier II)
 * M35 2.5 Ton Truck

Technology
The HECU's technology is mostly based on conventional and unconventional military practices such as vehicle support, artillery support, fortification and traps in the Half-Life expansions.

PCV
The PCV was a vest to protect HECU forces from the full force of projectile trauma, hazards or blunt strikes from alien forces and the suriviving members of the facility. It also features a Greger counter and surpasses the HEV and Security Vest at nocturnal operations by a 180 degrees of night vision. It also has more storage capictity than both Securtity Vest and HEV and can charge from both military and commerical suit charging stations.

Tactical Map
Utilized by HECU forces and by Gordon, the Tactical Map role is to coordinate air strikes against targets. It makes its first and only appearance at the end of Surface Tension where it was to destroy a Garguatua and destroy the obstructs in the way. The operation of the Tactical map is quite simple as you move the crosshair by moving two switches and and the start button which F-16s bombard the area of fire.

Behind the scenes

 * Originally, some HECU soldiers were to be smoking. It was cut but brought back in Opposing Force.
 * Originally, the HECU was to feature a powerful minigun-wielding soldier. He was nicknamed "Human Sargeant" (sic).
 * A unnamed two-legged robot with a single red eye can be seen in early screenshots. It is however unknown if this robot was to be a part of the HECU forces. It is almost identical to the Zentraedi Tactical Battle Pod from the TV series Robotech, which may be the reason why it was cut. It is a possible inspiration for the Hunter.