Chapter 3 Return Start Chapter 3, after entering the room, use the catapult, and meet Wheatley again. There are several more catapults needed to be used here. After the ceiling above the catapult is in place, open a blue portal on the ceiling and a yellow portal above the steel plate.

Use the catapult to go up. Be careful to keep the blue portal. After going up, open a yellow portal door on the inclined surface of the laser emitter, then go down to use the catapult, and bounce it to the oblique facing platform to use the switch. The box was released on the platform opposite.

Then open a yellow portal on another incline, which is flew to the platform of the box with a catapult. Then put the box on the laser emission route so that the laser light hits the white wall. Then use the catapult to reach the platform at the gate, and then open two portals on the front and back of the wall where the laser hits, which is the laser hitting the receiver.

进入下一个房间，使用弹射器上去，然后朝底下的地面开个蓝色传送门，然后在左边的白墙高处开个黄色传送门，然后跳下去通过传送门到达箱子那里，捡取箱子，使用弹射器，把箱子放到接收器那里挡住激光。 Then use the catapult to get to the switch and use the switch to release the box with the mirror. First open a yellow portal opposite the receiver. Then pick up the box and come to the laser emission place just now, open a blue portal on the opposite white wall to make the laser pass through the portal and shoot it on the receiver. Then take the mirrorless box and use the catapult to reach the gate and place the box on the red button. After entering the next room, you will encounter a blue beam belt and you can stand on it. First open a blue portal on the white wall of the beam belt.

A yellow portal was opened on the white wall next to the opposite door, and used the light beam to bring it over, open the mechanism, and release the box. Then come back and open a yellow portal on the white wall on the left, which is the beam belt that penetrates into the hole on the right. Go down through the portal. After going over, open a yellow portal on the white wall in front, run over and then open a yellow portal on the white wall on the right. Don't let the character fall into the water during this process.

Catch the box with a beam belt. After picking up the box, you came out of the portal. Open a yellow portal on the white wall on the right, so that the beam belt passes into the gap on the left, and then pass the portal to the red button on the left. Place the box on the button. ThenOpen a yellow portal on the white wall at the bottom right, jump to the beam belt and go back through the portal, then open a yellow portal opposite and use the beam belt to pass by. Enter the next room and wait for GLaDOS to open the door. After entering, open a blue portal on the side, and then a yellow portal on the white wall above the beam belt. This way you can get on the beam belt. Open a blue portal on the white wall where the beam belt arrives. Then open a yellow portal on the white wall at the bottom right so that the characters can reach the mechanism, and at the same time, they need to follow the boxes released on them.

Take the box back to the beam belt transmitter, open a yellow portal on the white wall below to get it to the gate. Enter the portal and place the box on the button. Entering the next room, you will start to encounter a white robot turret. Press the E key behind it to pick it up. When you put it down, you can invalidate it. There is also a turret on the left front, and you need to pass the portal above it and go down behind it to destroy the turret. Then open the portal below the front turret and get it away.

Open a portal on the white wall behind the fort in the front room and pick up the box. Once past, the turret on the white floor can open a portal under it to get it away. Then open a portal above the red button, detour the other two turrets behind and destroy them one by one. Finally put the box on the button. Enter the next room and move the refraction box to the following position so that the laser passes through the mechanism and shoots it onto the opposite wall. Then open a portal on the wall hit by the laser, and then open a portal on the white wall that is in a straight line with the other two mechanisms, so that the laser can pass through the three mechanisms. Enter the next room and first open a blue portal on the white wall of the beam belt. Then open a yellow portal on the white wall to the right of the turret to block its view. After running over, remove the portal and destroy the turret.

Open a yellow portal on the white wall in front to block the view of the turret on the right. Run to the left and open a yellow portal on the white wall in the middle, so that you can get up with the catapult. After going up, they arrived at the boxes surrounded by the turrets and killed the turrets one by one. Then place the box on the red button. Then open a yellow portal on the wall to the right of the turret in front to block the turret's view. Go and kill the turret. Once you enter the next room, skip the beam of light emitted by the turret first. Stand on the red button and turn on the laser, then open a blue portal on the ground hit by the laser, and then open a yellow portal on the wall in front of the right to make the laser hit those turrets to destroy them. In the past, picking up the refraction and using laser to kill the inside of the turret and touching the mechanism to open the door. Enter the next room and open a blue portal on the white wall hit by the beam belt.

Open a yellow portal underneath so that you can go up. After going up, open a yellow portal on the white wall on the right, pick up the box and place the box on the beam belt to block the laser while also above the red button. Then run to the elevator and change the position of the blue portal. The beam belt below the box disappears, and while the laser recovers, the box also reaches the button. In this way, the elevator went up and the door opened.

Get the elevator through the gate, and the third chapter ends.