We exit the elevator. There's a locked door ahead, and a valve is missing near it. We turn the valve to the left of the elevator. In the room, among the boxes, we find a portable valve. We take it to the exit door and turn it.
We emerge onto the surface. In the destroyed square, we see Dr. Kleiner's speech on the screen. We go to the left corner and clear the metal sheets out of the way with the gravity gun. In a narrow alley, we fight flying drones and Combine special forces. We take the automatic rifle from the enemies.
We exit to the street, where antlions constantly appear. We push cars into the pits to prevent the insects from appearing.
KDEL Building
We enter the building. There are laser traps inside; we activate them to blow up the Combine ambushers. We proceed to the back room, where there are swinging pipes. We place rocks and various debris on one end of the pipe. Stand on the fixed ledge to the left, jump onto the pipes, and quickly jump to the cistern with the valve. Turn the valve off the fire in the first room and head to the stairs.
There are several zombies on the second floor. Throw the crates forward to detonate the laser traps. There are also two mines here that can be reprogrammed. A sniper will be shooting at us in the second half of the floor.
Go down to the street and run from cover to cover. If you're trying to get the "One Bullet" achievement, don't shoot from afar; instead, get to the sniper's position and throw a reprogrammed mine or grenade through the sniper's window.
Under cover
Alyx climbs up and takes a sniper position. We climb the stairs to the other street and move forward, while Alyx will be picking off zombies.
There's only a small dead end to the left. We go right and enter the building. On the top floor, Alyx will also be killing enemies through the windows.
On the next street, we push the car into a pit to block the insects from spawning. To the right, on the second floor, a machine gunner has taken cover behind some barriers; Alyx can't hit him. We use the gravity gun to tear off the metal sheets to dismantle the machine gunner's cover. We approach the fortified wall of the Combines. Once we've killed all the enemies, Alyx will catch up and open the entrance to the building.
Combine Barracks
Inside, we navigate the narrow corridors, destroying the Combines. In the large room, we grab the pulse rifle. We run along the top floor and jump down.
Outside, the Combines are fighting a huge antlion. First, you need to run forward and cover the two insect pits with cars. After that, you can destroy the boss. If you're working on the "One Bullet" achievement, you'll need to throw explosive barrels at the insect or wait for Alyx to kill it.
After defeating it, the gates will open and Combine squads will attack. Alyx will man the machine gun; you can wait near her until the firefight ends.
Ventilation
We reach the ditch behind the gate and head into the left basement. Here, we detonate the dangerous barrels from afar and remove the mine. There's a closed door ahead, and to the left of it, we climb into the ventilation hatch. If we climb the ladder in the vent, we'll fall back the way we came.
If we crawl forward, we'll fall into a room with multiple lasers. Carefully climb out of the ventilation pipe through the back exit. Jump out of the room using the barrels and into the elevator. But the elevator will break off and fall into the water. Open the hatch in the ceiling, surface, and go to the lower floor.
While crouched, we pass under the lasers, jump through the window into a dark room, and kill the poisonous headcrab. We climb through the vent to the upper floor. We jump through the elevator shaft to another ladder.
We find ourselves in the ventilation on the upper floor. Through the hatch below, we see a laser directly below us. We break down the hatch, everything below will explode, only then can we jump down. We turn on the switch on the wall, the doors will open, and Alyx will join us.
Basements
We can take mines and throw them into the next rooms; there are lasers everywhere. We climb the inclined stairs, approach a closed door, and immediately run back. Combines will burst in; we destroy them.
We go upstairs and find a new weapon on the shelves—a crossbow. In the upper left corner, we pull the plug from the outlet with the gravity gun; this will disable the force field below. We go there and exit outside.
Together with the resistance:
On the streets, resistance fighters are fighting the Combines using grenade launchers. If one of our allies is killed, we pick up their grenade launcher. After defeating everyone, we enter the open side door in the center of the street.
In the courtyard, we enter the underground headquarters of the Humans. We listen to Kleiner on TV. We go up the landing and kick down the door at the top. The floor in the room is shaky; if we step on it, we'll fall to the floor below. Here, we'll have to fend off zombies using the furniture. In the next room, through a crack in the floor, we can overhear a conversation between a young man and a young woman from the resistance. We go upstairs and continue through the same room, but this time we go around the gap in the floor on the left side.
We reach the room where Barney's squad is hiding. He hands us a new weapon—a crowbar. We cross the lowered bridge. We reach the next bridge through the apartments. In the circular lifting mechanism, we break a board, which lowers the bridge.
Hospital
In the corridors of the hospital, we fight Combine harvesters, while a helicopter fires at us through the windows.
We reach the attic; there's a chest with infinite missiles. With these missiles, we need to shoot down the Combine aircraft. There's a destructible floor here, and the helicopter will gradually destroy it with machine gun fire, making it increasingly difficult to reach the chest, so you need to take down the boss as soon as possible.
We continue along the hospital corridors. Here, the Combine are fighting zombies. Through one of the offices, we exit into the "Recovery" corridor. We bypass all the offices, after which the zombies will break down the doors in the center, so we go there.
We jump down to the floor below and fall into the flooded basement. We climb up and jump through the window. We cross the water; there's a bridge here that lowers into the water under our weight. In a dead-end alley, we find a blue empty barrel and place it under the edge of the lowering bridge. We see a switch on a support near the far wall; it opens the doors behind us, but this electrifies the water, so we must avoid touching it. We run along the bridge, which we propped up with the barrel, jump to the island, and then onto the pipes on the right. We enter the open doors.
We find ourselves in a room with locked doors. There are mines on the shelves; we can throw them at the zombies through the windows or place them in front of the doors. The zombies will break down the doors, kill them and exit. We reach a corridor covered by two machine guns. We hide from them behind the columns, pull out the mines, and throw them forward. We reach the force field, use the gravity gun to pull the cable out of the socket, after which the machine guns will turn off. The final chapter awaits .
Source: gamesisart.ru