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The companion cube.

The vital apparatus vent will deliver a weighted companion cube in 3...2...1.


This is your introduction to the weighted companion cube. It will stay with you for the entire chamber, providing any assistance you require. Throughout the test, GLaDOS will make odd remarks about the companion cube, indicating how it is not alive, as if you are very attached to it and insisting that it is going to talk or do things.

Overview of the main puzzle area.

After picking up the cube...

This weighted companion cube will accompany you through the test chamber. Please take care of it.



Use the cube as an intermediate stair.

Using the weighted companion cube[edit]

The first area is about using the weighted companion cube to help get you through to the platform area by standing on it and using it as a shield. When the cube drops from the transport tube, pick it up. You will notice the steps are too high to jump on, so you will have to set the cube down, climb on it, continue to the step, and then grab the cube and do the same thing for the next step.

The companion cube will protect you.
There are 2 reachable cameras (ignore those on non-portalable surfaces):
  1. Next to where the second pellet hits the wall.
  2. Above the doorway to the small pellet launcher room.

Once at the top, you should now see a corridor with energy pellets bouncing back and forth - hold the cube in front of you to deflect the pellets harmlessly. After going through both corridors, you should reach the main test area where you need to raise three platforms, by bringing pellets to the three receivers. These can be done in any order, but the way described here is probably from easiest to hardest.

Receiver 1[edit]

Portal placement for first receiver.
There are some things to note about the order of these three tasks. First off, the platforms are not connected to specific receivers, and thus whichever receiver captures a pellet first, platform 1 will rise up, then 2, then 3. Also, receiver 2’s pellet will always shut off the launcher located in that room, no matter which pellet actually made it in there. Lastly, whichever is first out of receivers 1 and 3 will shut off the second corridor’s launcher, and then the remaining receiver will shut off the first corridor’s launcher. This can be very useful information for the bonus challenges.

One of the platforms is easily raised without assistance from the cube. Place a portal within the second pellet corridor (the one easiest to get to from here, where the pellet hits the wall), and the other on the angled platform across from the angled platform with the pellet receiver. The pellet will bounce off the ceiling and hit the receiver.

Receiver 2[edit]

Deflect with your companion.

The doorway under the camera contains a pellet launcher firing a pellet perpendicular to the receiver, but there is no method to place a portal. However, you can bounce the pellet using the cube into the receiver.

Portal into the secret area.
A lot of info... a lot of questions...

Before you travel back up to the ledge, notice that there is an area behind the ground-level extended panel. While you cannot crawl into this, you can create a portal inside the area and explore. Some interesting pictures and writings may make you wonder what all has gone on in these test chambers in the past.

Receiver 3[edit]

The radio is located underneath the third platform, and cannot be grabbed until after it is raised. Take it to the cube incinerator.
Teamwork opens the two doors!

In the final side room, there is a pellet receiver blocked by 2 doors, each powered by a button. Go ahead and portal back up to the ledge, and shoot a portal on the wall where the remaining pellet is bouncing. Come back down and shoot the other color portal on the extended panel. You can place the cube on the raised button, however if you simply stand on the second button, the pellet will run into you. Either stand on the very side edge of the button, or wait until the pellet just passes, then quickly stand on the button to open the door before the pellet hits it.


Gamerscore points
Do whatever it takes to survive.

Once all three platforms are raised, shoot a portal onto the ceiling or high wall, and bring the cube with you. Jump across all three platforms and onto the next level, and then place the cube on the next button.

GlaDOS will explain that you must euthanize the cube by placing it in the incinerator. Proceed into the open room and press the button to open the incinerator, then quickly grab the cube and drop it in. The chamberlock will then open.


In the advanced chamber, the weighted companion cube has become a ball, the platform activations are tougher, and an extra step has been added towards the end.

You may quickly find that the ball seems to have a mind of its own, in that even if you set it down in a stationary setting, it may roll around aimlessly anyway. Do your best to climb the stairs as before, and then rebound the pellets as you move through the halls.

The first receiver has a glass barrier preventing the normal method of placing a portal on the angled platform. It is easy enough, however, to place one on the ceiling above the angled platform, and the pellet will bounce off and into the receiver.

The second receiver has a glass barrier as well, making it more difficult to bounce the pellet in. Just use trial and error, bouncing it at different angles with the ball, and you’ll get there. Try not to get hit in the process.

The third receiver has both buttons in the back, at a higher level. Hold the ball onto the first door’s button, wait for the pellet to pass, then lift the ball off so that the pellet is bouncing in between the doors. Quickly move the ball to the other button before the pellet disappears, and it will bounce into the receiver.

Alternately, if you knock down a camera, you can place the ball on one button, and hop onto the camera, giving you enough height to hop to the other button yourself.

As you cross the platforms, you’ll notice the normal exit to the right is no longer there. Proceed to the left instead, and you’ll find an accuracy fling test. You can’t just fling from the top, as that will shoot you out too high. Instead place the portal on the seam between the top two panel layers. Drop the ball through first to make sure it’s accurate, and then fly through yourself. A simple portal on the wall to get up, and it’s off to the exit as normal.



Bronze at 4 portals

Proceed with the cube to the three-platform area.

  1. Blue portal on the second pellet’s scorch mark.
  2. Orange portal on the angled platform to direct the pellet into the receiver.
  3. Blue portal on the first pellet’s scorch mark.
  4. Orange portal on the extended ground level panel. Activate the other two platforms as normal, walk through the orange portal with the cube, and proceed all the way to the exit.
Silver at 3 portals
  1. Blue portal on the first pellet’s scorch mark. Proceed with the cube to the three-platform area.
  2. Orange portal on the angled platform to direct the pellet into the receiver. Notice that this deactivates the second pellet, and thus there is still a pellet entering the existing blue portal (see sidebar in this chamber’s walkthrough).
  3. Orange portal on the extended ground level panel. Activate the other two platforms as normal, walk through the orange portal with the cube, and proceed all the way to the exit.
Gold at 2 portals

Solution 1:

  1. Blue portal on the first pellet’s scorch mark. Proceed with the cube to the three-platform area.
  2. Orange portal on the extended ground level panel. Activate the second and third receivers as normal. In this situation, the angled platform receiver is trickiest. Place or hold the cube such that the pellet will bounce off the edge of it, and hopefully rebound into the receiver eventually. This will be a bit of trial and error. Then walk through the orange portal with the cube, and proceed all the way to the exit.

Solution 2:

  1. Blue portal into the room with cameras behind the extended ground level panel.
  2. Orange portal outside. Retrieve all 4 cameras.
  3. Go to the exit ledge, stack 2-3 cameras at the bottom, the cube on top such that you can get the cube while crouched when you get on top, and another camera on that cube.
  4. Jump up the stack, remove the top camera, crouch and retrieve the cube. Proceed all the way to the exit.


Under normal walking conditions, it takes about 90 steps to get to the main area, and about 70 to get from the first platform to the elevator, so first, you probably want to adjust your walking. Methodically stepping and jumping (not jumping constantly) can increase the distance you cover on average per step. Past that, these amounts are not easily reduced without glitches, so this is really just about how few steps you can activate all the platforms in. This is where the side note above really helps out. Putting a portal on the first pellet’s scorch mark on your way past the first time is pretty much essential to get even bronze. Once you get to the main area, jump down with the cube. Place a blue portal on various walls, as you attempt to bounce the pellet that comes through into either of the side rooms at an angle. With enough tries and a little luck, you will be able to activate both of these receivers without moving more than enough to get the cube in the way of the pellet. Neither of these will deactivate the first launcher, so simply place a portal on the angled platform (or the ceiling above it) to bounce one into the easy receiver.

Bronze at 215 steps
Silver at 175 steps
Gold at 150 steps


This chamber involves a lot of walking on non-portalable surfaces, so you'll need to figure out how to move as fast as possible. Most people find that jumping constantly is slightly faster than walking. Try it and if it works for you, use it here. Others jump at every other step. Of course, if you've mastered Accelerated Back Hopping, use that, but if you're looking for help here, ABH is probably not in your bag of tricks.

Another annoying thing about this chamber is that you can make what feels like excellent time up to a certain point and then have to stand and wait for an energy pellet to arrive. Before you can improve your total time, you have to get to that point sufficiently sooner to be able to use an earlier pellet.

You can save and load the game in challenges, so whenever you get to a point in less time than before, very quickly hit the save key and store it away so you can try working forwards from that point over and over again through the next section. Keep multiple best-time saves, in case you find you can't improve in the later sections and have to go back to an intermediate one and try to improve that.

Bronze at 2 minutes, 20 seconds (140 seconds) : You should be able to get this medal by refining the basic Walkthrough, above, and executing it promptly and without error. Put the orange portal on the wall where the first pellet’s scorch mark is and leave it there until all three platforms have risen. You will be able to use two pellets from the first emitter to activate receivers so don't bother with pellets from the second emitter (in the second corridor) at all. When you emerge from the corridors, immediately place the blue portal on the angled surface as described in the Walkthrough for Receiver 1 and just keep on going into the small side room to deal with Receiver 2. Obviously, in there you want to deflect the pellet into the receiver with the cube as quickly as possible. When you come out, check that while you were gone Receiver 1 has been activated and move the blue portal to the extended, ground-level panel. Continue with Receiver 2 and the Exit according to the Walkthrough.

Silver at 1 minute, 45 seconds (105 seconds) : To advance to the silver level, you need to shave seconds off at every opportunity, execute each move perfectly and move quickly from place to place. At the start, head past the Vital Apparatus Vent and just through the doorway. Put the orange portal on the wall at the end of the corridor while you're waiting for the cube to drop. Turn back, catch the cube before it hits the ground and take it to the steps to climb up. In the first corridor, be careful to deflect the pellet so that it travels horizontally back along the corridor. Specifically, you don't want it to go where it might hit you as you make the turn at the end and climb up the steps to the second corridor. This one is actually wide enough that if you keep to the right the pellet will pass you on your left. Alternatively, go down the second corridor backwards. After raising the platforms, the fastest way to the first one with the cube is probably through a portal on the ceiling directly above it. Try to jump from platform to platform in a continuous rush, i.e. without pausing to gather yourself on each one. Practice putting the cube on the last button sideways so you don't have to stop before continuing to the incinerator button. Finally, if you can throw the cube with any accuracy, use this to toss the cube into the incinerator to shave off a second on your way to the chamberlock.

Gold at 1 minute, 27 seconds (87 seconds) : Reaching gold level means shaving eighteen seconds off the already difficult silver time. Below are three ways that you can try to achieve this.

Gold by Sheer Speed : To give an idea of the speed required for gold level, you should be at the top of the stairs with your cube, ready to jump down the corridors, about 20 seconds in. For those stairs, if you jump backwards off the cube, you will be able to grab the cube as you jump and then continue. You should be sending the pellet into Receiver 2 in the side room at around 40 seconds in. Receiver 1 should be activated as before. In the room with Receiver 3, hurry to put the cube on the button at the back, tossing it up if you can, and, if you are on schedule, you should be able to make it back to the floor button in time for a pellet that just came out of the blue portal in the extended, ground-level panel to travel through the door that is opened by that button. Go back to retrieve the cube; at this point you should be just under a minute in. Get back to the portalable surfaces in the main room. Drop the cube, shoot a portal above the first raised platform, and the other near the cube. Grab the cube and take it through onto the platform. You need to get the cube on the last button at around 1:12. That leaves you fifteen seconds to open the incinerator, toss the cube in and get to the chamberlock. These are very difficult times to make unless you have mastered a technique for "walking" very quickly.

Gold, Bypassing Platforms : Another option is to take the cube through to the rising platform area and place it in the right-hand corner of the alcove directly below the path to the final floor button (that leads to the incinerator button). Head back to the main testing area without the cube, placing one portal on the right wall as close to your cube as possible. Approach the camera on the wall ahead and get into a position so you can catch it while it is in its normal orientation. Fire the second portal on the wall behind the camera to detach it and catch it mid air. Take it back to the cube and place it on top of the cube so you have a tiny set of stairs up the right corner. Hop up and make your way to the final floor button, placing the same color portal you used to remove the camera next to the button to fall through. You will exit through the low wall portal near your cube. Grab it and go back through, place on button, activate the incinerator, toss the cube in and head to the exit.

Gold by Patience and Perseverance : Play as for silver, above, up to the point where you place the blue portal on the extended, ground-level panel. You must play fast enough that there is a pellet on its way to you when you do this. Save the game. Instead of entering the room with the two doors and two buttons, stand to the left of the doorway. Hold the cube so that the pellet will strike its edge and be deflected through the door towards the right-hand wall. If the pellet travels at exactly the right angle, it will enter the receiver behind the doors and make the last platform go up. Obviously, it's going to take lots of trial and error before you get into the exact right place to make this happen. Use one or more saved games so that you can adjust your position by tiny increments. When the pellet looks to be going the right way, immediately make a run for the exit. It's no use waiting to see if the last platform rises, you need to act as if it will and portal up to the first platform as soon as the pellet strikes the cube. Put the cube down, place the portals and dive through, picking the cube up again. If, when you get to the third platform, it isn't rising, try again from your saved point. And again. And again. Eventually, with patience and perseverance, you will get it to work. Then, just hope that your time to the exit gets you the gold medal.

No Cheating SpeedRun in One Segment for Mere Mortals[edit]

This is a difficult chamber to speedrun in a satisfying manner because of all the walking involved. Most of the advice given for the time challenge, above, applies to speedrunning. However, since you will already have about fifteen minutes invested when you reach this point, you will not want to do anything that puts you at significant risk of getting killed. It's always a good idea to quicksave before facing danger because then, if things go wrong, you lose only the time to load the game and go back to try again. This will probably spoil your overall time, but it's less frustrating than dying. Just call it a practice run.

So, in the first corridor, don't deflect the pellet off in some direction where you can't be sure you won't run into it later. The safest thing is to send it straight back along the corridor. At the end, you go down four steps, turn 180 degrees to the right and up eight steps into the second corridor. The first pellet will be above your head as you turn, but you do not want it to hit you as you climb the steps. If you're making good time, the second pellet will leave its emitter and catch up with you in the second corridor. Either let it pass on your left or go backwards so that you can deflect it away.

The next danger point is in the side room with Receiver 2. It goes without saying that you want to come back out of this room alive. You just need to practice until you know where to stand to deflect the pellet into the receiver and not have it rattling around the room. Make sure you are holding the cube in the same orientation every time you try this. Most people will probably want the cube straight, so that they have to stand at 45 degrees to the pellet's path, but you can also see if holding the cube at 45 degrees and standing square in the room works better for you. If you have to put the cube down and pick it up again to adjust its orientation, that will, of course, cost you time, so you need to pick it up correctly before you start down the first corridor. That's why holding it square is probably best.

In the two-door, two-button room, it's easy enough to avoid the pellet, but you also want to make sure the first door is open to let the pellet pass. Stand to the side and watch the pellet pass over the button. Time your move forward so that you are on the button at the critical moment and, without pause, keep going in the direction of the cube to retrieve it.

Techniques for the time challenge that involve saving the game and retrying from that point won't, of course, work in a speedrun. If you can get into the exit chamberlock within 1 minute and 45 seconds from when the entry chamberlock door opens (the silver time), you're doing OK.