Disclaimer: I do not own Half-Life, Half-Life 2, Valve, or any characters/objects/names/etc. owned by the aforementioned Half-Life, Half-Life 2, or Valve.
Author's Note: Events described during the 7 Hours War is merely speculation, and is completely arguable.
The Black Ops assassin leaned over the balcony, one hand on a .357 Desert Eagle. In the street three stories down, two Crab Synths were butchering a squad of marines. The marines, all wearing masks and green-and-black fatigues, scrambled over abandoned cars and trucks. The synths knocked the vehicles away with their sharp mandibles; some of the cars were thrown right into the humans, sending them through the broken glass windows of a café like cheese through a grater. A mine exploded under the single-toed foot of one of the Crab Synths; the explosion removed the large limb, leaving two smaller ones and another big one. Moments later, the Crab self-replicated the limb and rebuilt itself. The marines, now in full retreat, fled back up the boulevard and disappeared into the fog of war.
The assassin pulled back from the balcony, and ducked into the hotel room. The bed was unmade, and an open suitcase lay beside a reclining chair. The flickering television displayed a grim reporter standing before a scene of devastation: a skyscraper behind him had been obliterated, and several long pieces could be seen laying a path into the distant. Most of the buildings had been cleaved in two, allowing a view of the chaos behind the reporter: several tall, three-legged and fleshy synths were carving a path through the city. "At four hours since our newfound enemy teleported onto Earth, the aliens have deployed a large force of 'walkers', which are engaging allied troops on many fronts -" the reporter's voice became garbled and the image vanished, being replaced by an overhead view of the battle. The camera zoomed in on one of the walkers, and a stream of blue pulse fire rewarded it. The fire missed the camera but hit the helicopter; smoke fogged the picture, but the screams of the camera operator could be heard over the erratic chopping. Suddenly, the television blacked out, along with the overhead lights inside the hotel room. The assassin continued into the dark hallway.
The Black Ops assassin crept passed the elevator and entered the stairwell; two flights down was a door with a picture of a flame printed on it. The assassin opened the door and stepped out onto the fire escape. In the alley below, a flaming corpse provided enough light so the assassin could see a headcrab zombie sprawled against a brick wall and a manhole beneath its feet. The .357 dealt with the zombie; the assassin dragged the body and dropped it in the flames before prying off the manhole cap and dropping in.
With a splash, the assassin landed in the darkness of the sewers. A gloved hand switched the goggles to another setting: night vision, which revealed a bulky figure standing at the other side of the duct. It wore a trench coat and had glowing orange eyes beneath a spherical helmet. It was tall, and held a sort of tube in one shadowy hand. Hearing the high-pitched gasp from the assassin, it raised the tube and received a bullet to the helmet. It stumbled backwards and smacked against a grate, the eyes rapidly dimming. With a small groan, the creature died, and the assassin continued through the catacombs.
The assassin climbed the next ladder it came to, and pushed the manhole open. Immediately, the sounds of explosions, screams, and shouts could be heard topside. Without hesitation, the assassin rolled out into the open, which was a long tunnel with emergency lighting decorating the ceiling. Dozens of civilians and marines were running from something; the assassin turned around instantly, holding the Desert Eagle into the face of another walker-synth. Its three legs were bent, and the "elbows" were above its fleshy "head". The Black Ops assassin holstered the Desert Eagle and began sprinting in one fluent movement. Pulse fire erupted from the synth, and concrete exploded where the shots landed.
Sprinting from cover to cover, the assassin finally merged with the crowd as they fled out into the open street. The buildings here were still intact, surprisingly; the huge blue-ish alien citadel stretched into the sky very close to where they were - even more synths were seen marching around the area. There seemed to be a disturbance on the other side of a law firm on one end of the road, but the smoke from a burning APC clouded the air around it. A long flying synth zoomed overhead; it had a helicopter-like spinning blade in the back, keeping it mobile, and it had two small fish-like limbs towards the front. Just like on the walker-synth, an object resembling a stick protruding from the front. It disappeared behind the buildings, and the crowd let out a collective sigh of relief.
The assassin pushed through the citizens, some of which had realized that the striding walker was
still behind them. Emerging from the panicking humans, the assassin began sprinting towards a law firm at the other side of the beaten road. The strider synth unfolded itself from the tunnel behind the assassin, pulse cannon still roaring. There was a distinctive noise and a huge purple beam exploded from the synth's head, demolishing a large portion of the street and a nearby McDonald's. The creature disappeared from view as the assassin slipped into the law firm and began maneuvering through the hallways. After trotting past several offices, an emergency exit appeared on the other side of the corridor: the assassin left through it, and immediately stepped into another war zone.
Allied helicopters had deposited several Abrams tanks and a large amount of marines only a small distance from the alien citadel, apparently in a final effort to cut the enemy off at its source. There was a number of felled synth burning at one end of the street, including two of the tall ones, one Crab-Synth, and four Mortar-Synth.
A marine bearing a GB36s assault rifle approached the assassin. "Black Ops, eh?" he said, eyeing the skintight leather suit with a grin. "What do you wan'?"
She told him, gesturing at the citadel. He chuckled, and muttered, "Yeah, good luck with tha'." Louder, he continued, "We have a few APCs and scou' cars up ahead, holdin' off anothah charge of Striders. They'll help you along, but we're not going into there, jus' yet. You bettah get wha' you wan' done, fast, 'cause we'll be artillery bombardin' the citadel in a few hours."
The assassin nodded, and trotted forward, sticking to the shadows. Several marines began yelling and there was a bout of explosion toward the other end of the make-shift camp, but the disturbance was shrouded by the fog. Turning the corner and navigating the debris of a shattered statue, the assassin came to the road block the marine had mentioned. An Abrams tank had rolled up, but most of the scout cars were lying in several pieces. Most of the marines had retreated into the two buildings on either side of the intersection: a dark grocery store with a broken billboard protruding from roof, and a French restaurant with weaponry bristling from every open space. Bits of armor were stacked upon the roof and welded into place around the edges; apparently, the humans had turned then restaurant into a bunker. The assassin entered an alley and opened the emergency exit door and slipped in without alerting the marines; instead of approaching them, she retreated to a the dark kitchen and listened in.
"Another wave of Striders are incoming, sir," reported a young voice.
A gruffer one answered, "Are the snipers in position?"
A third, loud voice, replied, "They are, and have attached the laser designators to the barrels. The helicopters and the planes are ready for the signal."
Gruff grumbled, "The trip mines?"
Youngster said, "Placed, sir. The demolitions tech packed an extra few dozen packages of C4 in 'em, we're callin' it C12, get it, sir - "
Gruff ordered, "Head over to the grocery store, George, and check on them. Where are the Striders now?"
Loudman answered, "Almost here, sergeant. A few Crabs have joined them."
Sergeant Gruff said tiredly, "Have the APCs target them. Maybe if we get enough lead into 'em, they won't be able to repair themselves."
Loudman said nothing, but there was the sound of boots stomping and a door opening and closing. A few moments later, explosions rocked the French restaurant, followed by a long artificial groan. Gunfire erupted from the street. After a few minutes of nonstop explosions, gunfire, and pulse fire, something slammed into the French restaurant. Several more crunches followed, ranging from the French restaurant to the grocery store. The assassins stepped out of the kitchen to see a hole in the ceiling and a black, cylindrical object on the tile. Headcrabs began filing out of it, to the shouts of the marines.
The Black Ops assassin exited through the door she had entered through, and heard the same sound she had heard after exiting from the tunnel with the Strider in it. One of the alien aircraft! Looking around, the assassin saw the synth vehicle fly low, screaming through the street. "Gunship!" someone screamed, followed by the sound of more pulse rifle fire. There were also a dozen small flying synth objects, spherical, and with a rope of tubes and wires coming out the back. They began firing tiny pulse rifles at the French restaurant, and flashing bright lights.
The assassin returned to the alley and took note of the fire escape: the ladder was raised just above her grasp. She stood back and leapt to the first rung, and clambered up the ladder to the roof. Stepping over the armored plates the marines had dropped onto the roof, the assassin crept to the edge of the building. Heavy rain drops began to fall, just as another fleshy flying synth appeared through the fog. It was much wider than the gunship, and didn't have a propelling blade. It had eight spider-like legs, with blue lights beneath them, probably what was keeping it afloat. There were two tail-like limbs on the back of it, and it resembled a flying, alien whale. The legs held tightly onto a Strider.
As the second flying synth passed by the assassin, she jumped onto the fleshy back, and it let out a loud groan. Dropping the Strider like the flying synth had been shocked, it passed over another building opposite the grocery store and climbed into the air. The assassin pulled out two combat knives and stuck them into the brownish back; sparks of electricity and an oozing green liquid appeared from the slices, but the assassin held tight onto the knives hilts. The flying creature spun in midair, almost dislodging the assassin, but the knives held, and the synth dropped back to street level. In a panic, it crashed into the rubble of a car dealer. It let out another piercing groan; the assassin quickly pulled out the combat knives, just as the alien synth began to recover; she jumped off the beast and sprinted to cover as it ascended into the fog.
The Citadel was now much closer, visible through the fog - the Black Ops assassin could hear the sound of machinery below it. She returned the knives to her hilt and pulled out the Desert Eagle as she crept toward the Citadel. There was purple lighting here, occasionally - the portal storms that had brought the aliens had not yet ended. The assassin approached the Citadel, and soon found that there was a massive trench between the street and the huge alien structure. Many of the small round objects that the assassin had seen at the road block were floating up from it. One appeared right below - and the assassin leapt, planning on trying the same thing against it as she had done against the alien flying synth. She grabbed onto it, and it fell a couple of meters before recovering. It bleeped, and began firing the machine gun wildly as it ascended. After a few straight minutes of this, it ducked into a large opening in the Citadel, and began spinning and bleeping louder. The interior of the alien building was empty, except for a few flying slug-like creatures, which disappeared as soon as the assassin entered. The spherical object she held on to slammed itself against on of the huge walls, and began to smash her fingers against it. The assassin dropped, and landed on a walkway below. She fired the Desert Eagle at the little synth until it exploded.
The Black Ops assassin could see deep into the Citadel from here. There were many, many empty coffin-like pods belted to the walls, and walkways like the one she stood on everywhere. She jogged across the walkway, and entered through a sliding doorway. It felt like a science fiction movie.
Moving deeper into the alien structure, the assassin saw more of the slug-like creatures. Were these the true face of the enemy? After walking for a half-hour without resistance, the assassin came across a huge manufacturing depot. Gunships were under construction by the synth slugs, though most of them were not actually working. They seemed to be overseeing, or advising, the synths. The assassin caught sight of more of the synth-soldiers she had seen in the sewers.
The Black Ops assassin came to another doorway, much grander than the previous few. It opened, revealing what looked like a lab. There were a few more of the slugs inside. They looked to the doorway, but saw . . . Nothing. The assassin was now among the rafters, looking down on the slugs and their experiments. Three struggling humans were strapped to three of the pods she had seen earlier. There was an empty pod, too - the previous occupant was on a stainless steel table, stretched and disfigured by the slugs. Only the head was visible, now - what looked like breathing apparatus melded into its throat, and a suit of black armor around it. One slug took a white, skull-like helmet, and fixed it onto the former human's head. The breathing apparatus was obviously connected straight to the helmet, as it was mirrored on the mask. The helmet had orange eyes.
The assassin, enraged, dropped to the ground, and whipped out the .357 Desert Eagle. The slugs turned, their machine-like arms twitching. There was a clatter, and the assassin looked to the source of the noise: some sort of synth soldier had appeared in the doorway. It had the same helmet of the thing she had seen in the sewers, but without the trench coat. There were tan armor plates on the shoulders, abdomen, and legs, like the Crab Synth, but the rest was fleshy, like the gunship and Strider. It held a long pulsing spear.
The Black Ops assassin fired the Desert Eagle three times, at each of the slugs. She turned the .357 on the synth-soldier, as the slugs slumped against the cold floor. She fired three more bullets; two bounced off the armor, while one punctured the fleshy chest. The assassin reloaded and backed up as the synth soldier stumbled, then leapt into the air, landing right beside the assassin. It swung the spear, knocking the Desert Eagle to the ground - then, it brought the spear around again and stabbed it right into the assassin's stomach. She gasped, then coughed, as the synth-soldier dug the spear into the wall. Red mist appeared around the edges of her vision, as the soldier left her hanging from the wall. Everything went white . . .