We emerge at the top of the citadel, where Half-Life 2's plot ended. A second before the core explodes, the Vortigons appear and save Alyx and me, stopping time and teleporting us to safety. Afterward, we see the Vortigons shielding us from the G-Man, meaning we're now on our own.
Rubble
The Mechanical Hound digs us out of the rubble and hands us the gravity gun. We talk to Alyx; she doesn't remember anything about teleporting. We need to get out of the pit. We hit the fence boards with the gravity gun, causing the chain-link fence to fall, and we climb up it.
We talk to Eli and Isaac on the computer. We learn that the citadel is about to explode. We can slow down the core's reaction to allow us time to escape the city, but to do that, we need to return to the citadel.
Once the Hound clears the rubble, we crawl forward. We jump down onto the cliff, then turn left and walk along the edge. Along the way, we shoot down a car with the gravity gun.
We emerge into an open area, facing the chasm before the citadel. The dog brings the van, and we climb inside. After that, the dog throws the van into the citadel, and that's how we get inside. After landing, we go left down the corridor.
Citadel
We arrive in a room with electric doors. Crawl to the left, jump down along the platforms, and press the red button. Catch one of the round mines and return to the top via the elevator. Hold the mine in front of Alyx; she'll reset it. After that, throw the mine into the room with the stalkers on the right. After they're dead, we can unlock the door inside.
We see white combines ahead. Crawl to the left through the rubble-strewn corridor. We destroy the next rubble with the gravity gun. Jump over the railing.
You need to run along the catwalk, where a gravity field activates on the side. Wait for the field to activate and then deactivate, then quickly run across before it activates again.
We enter the control room. Here, we watch an old recording with Dr. Breen. Afterwards, we see the face of an alien creature on the screens. The capsule containing this creature passes under the floor and is ejected from the Citadel.
The next room has weapon-destroying devices on the walls. The device is destroyed by the gravity gun. This causes the gun itself to become much more powerful and turn blue.
Bridges
Ahead is an energy bridge, only half-powered. We see an energy ball at the top; we attract it and throw it into the receiving device on the lower left. When the ball hits the device, the bridge will activate, allowing us to proceed.
Ahead, we fight Combines. With the new blue gravity gun, we can attract not only small objects but even people. We throw Combines at each other or hurl them against walls.
A second, deactivated bridge lies ahead. Below, there's a transverse white laser, constantly spawning energy balls. We grab the balls and throw them into the holding devices ahead. We cross the bridge.
Near the third bridge, it's the same story, but the left device is covered with armored glass. To throw the ball there, aim slightly higher, at the wall above the glass; the ball will ricochet and land where it's intended. We run along a narrow path and jump over a chasm over a broken glass floor.
Freight elevator
There's a wall-mounted first aid kit on the right. To the left is the power supply for the force field; we rip the energy ball out of it. We can exit onto the platform. In the elevator shaft, we use the white lasers on the side to attract the energy ball and launch it into the receiver on the other side.
We begin to slowly descend the elevator. Large chunks of building debris fall from above; we need to push them aside with the gravity gun in time.
The elevator stops. We see the receiver behind glass to the side. To the right of it, we rip out two panels. We take the ball and throw it into the open corridor on the right; the ball will ricochet into the device. We deflect another falling piece of debris.
The elevator stops again. The device is blocked from the side by a paneled pillar. We rip out the control panels on the left and right. We launch the ball just to the right of the pillar, and it will hit the device. A stalker will emerge and deactivate the device. We take the ball and throw it at the white stripe to the left of the device. It will ricochet off the glass and kill the stalker. We activate the device again with the ball and head down.
We reach a stop. A huge piece of debris begins to fall from above. We quickly exit the elevator, running across the catwalk. The elevator will collapse, and we continue down the floor. Now on to the next chapter.
Source: gamesisart.ru