We're walking down a narrow corridor, and white combines are running out to meet us.
First floor
Downstairs, there are disabled bridges and a couple of stalkers. We need to take the balls from the beams and throw them into the receivers above to restore the bridges. But the stalkers will disable the bridges after a while.
We'll cross two bridges. After that, we need to place the balls in all three receivers and press the button behind the glass. This will cause all the bridges to rotate toward the center, and they won't be disabled anymore. We'll climb up to the floor above.
2nd Floor
Enter the side corridor and throw the ball at the receiver. This will trigger a laser installation, which will aim the laser at the core in the center.
Flying cutters will appear; pull them toward you and throw them at the walls to shatter them. Go to the end of the corridor that opens and break down the small entrance door on the right. Behind the glass is a pipe carrying energy balls. Climb into this pipe-like room and move forward, dodging the balls.
3rd Floor
Break down the entrance door and kill the enemies. Exit to the central room. The core is pulsating and burning through the platform around it. We need to run across this platform in time without touching the core. On the other side, activate the second laser.
4th Floor
We exit onto the balcony and jump onto one of the rotating petals above the core. We reach the next balcony, which is slightly lower, and jump off.
We knock down the doors and run along the long room, dodging the balls. This way we reach the third laser and activate it with the ball from the previous room. But the laser stops working. We jump into the hatch in the floor from which the laser emerged. Below, we see three fields where we need to place the balls. We find a crack in the ceiling and pull the balls out from there. We place two balls. Taking the third ball, we step onto the elevator and launch the third ball into place. After this, the elevator will rise, and we find ourselves back in the room with the laser. We throw another ball into the receiver above the laser.
All three lasers stabilize the core for a long time.
We return to Alyx through the corridor that opens. She contacts Judith Mossman. Judith has discovered another teleportation research lab somewhere in the north, but her expedition is being attacked. There's nothing we can do for now; we first need to save ourselves and get out of the city.
Evacuation
We take the elevator down. We escape from the Combine. We lock ourselves in a room with two mines. We grab the mines and hold them in front of Alyx so she can reprogram them. We open the doors ahead, and the mines kill the Combine.
We board the train. We drive away from the citadel. Along the way, the train crashes. We regain consciousness, making our way through the overturned train car while sitting. We free Alyx from the fallen stalker by pulling his capsule with the gravity gun. We escape the train .
Source: gamesisart.ru