Warnings Active: Orb Hitting Body, Orb Receiver, Dangerous Water, Don't Drink The Water, Cake

Like the section earlier, make one portal on the angled part of the floor that points at the receiver. For the other portal, wait until the orb has gone down and hit the angled surface to make the portal on that left angled surface. The orb will return going left-to-right instead of up-to-down and the portal will carry it up towards the receiver.

Quickly turn around and jump on the platform as soon as the receiver is activated. Duck under the first obstacle. Next, jump on the grated platform and wait for the moving platform to go underneath it, then jump back on. Jump onto the area with the button, make a portal on the wall, then press the button and make another portal on the wall next to the hatch (behind it, specifically). Wait until you can see the platform through the portal, then step back on.

Note - if you're good with portals you can skip this platform-hopping part by using portals to hop to the center platform, then from there to the button platform.

Now there is an orb bouncing across your path; put a portal on the left bounce point and then make another portal above and behind you (or, depending on where you put the portals prior, it might get stuck behind you, but either way it is out of your way). Now there will be a giant wall blocking you; put one portal on the wall and another on the side of the corridor that is visible past it. Stand at the far back of your moving platform, and when most of it is visible on the other side of the portal, jump through it (you must jump, as there is a gap). The "final test" is an incinerator; when you are in the room, make one portal within jumping distance to the left or right of you (remember to make it slightly lower, as gravity drags you down when you jump) and another on the "safe" area visible above you. Don't worry too much about the fire; you'll be safe for long enough to make your jump, at least.

Once in the safe area, make a portal on the floor and another at the top of the wall behind you. Use the recursive flinging thing (making a portal while in midair) to gain momentum and launch yourself across the pit. Continue through the rusty maintenance hallway. When you reach the stairway, make a portal on the wall on the lower and upper levels and go through (the stairs will break, indicating disrepair). Press the use key (default "E") to go through the door. Walk up the stairs until you see the locked door behind the chain-link fence. Make a portal on the other side of the door and another one within you reach. Go through and open the non-locked door. Shoot a portal through the fan (your timing needs to be right or it will hit a rotor instead) and then make the other portal on the floor near you. Launch a portal over the walkway visible across the pool of dangerous water and cross through. Then look back across the way to see another catwalk with a part at the end that is larger than the other ones (deeper, really). Make a portal above that, then put the other portal behind you and jump through. Go to your right and notice the "escape up" sign scrawled on the wall. Make a portal at the top of that wall above the sign. Place the other on the floor. Fling yourself across with the whole landing-in-the-portal-to-gain-momentum thing. Walk up the stairs to continue. Jump into the broken pneumatic tube. When you reach your destination, step onto the cube dispenser to break it open. You will be in an earlier testchamber; now that you have both portals, walk through the particle field, stand on the button, and shoot a portal through. Make another portal on the wall and walk through it. Walk into the now-empty elevator hole. Once at the bottom, make one portal on the underside of the raised section visible (it will be crawling room when you walk through) and make another on the bottom of the elevator landing area. Crawl to the right (towards the two platforms that raise themselves up). Stand on the higher of the two lifting platforms. Once raised, move the portal that was on the bottom of the elevator hole to the top of floor. Return to the crawling area and simply stand up through the portal down there. Jump out of the portal and stand o nthe giant pneumatic crusher thing. Ride it over to the other side (marked with an "escape this way" paint symbol). Shoot a portal through the grate, then return to the pneumatic thing. Ride it back to the top floor part and make the other portal on it. Fall through. Once past the grate, put one portal on the ground level and put the other on the wall right next to - and above - the raised area. Rather than launching yourself, jump diagonally out of the portal and land on the raised section.

You should now continue to a room with five crushing things. Stand on the middle one as it goes up and then shoot a portal into the tall room. Jump back down and make a portal on the wall at ground level. Walk through. Now you will be in a room with two ceiling-crushing things to your right and a tall expanse to your left (look up, through a crack in the ceiling) filled with crushing things (going sideways, not up). Make one portal on one of the crushing spots (the areas marked by cracked concrete). Look at the left side and notice the overhang above one of the crushers. Put the other portal there. Go onto whichever crusher you put the portal over and be VERY CAREFUL to get right into the portal and not get your arms and legs crushed. The crusher going up should time with the other crushers coming out, so you will probably land on top of one of the cylinders. Now jump onto the top of the overhang that you put the portal on. Look up (following the red escape sign) and notice the portal-able walls. Make a portal on the right-hand side (if you look up behind you there should be a walkway; aim towards that) and then put the other portal on the floor. Loop yourself through to get momentum. Continue onwards; when you encounter the hallways with the many crushing things (that are unavoidable) simply shoot a portal through them and then make one behind you. There will be two hallways of this nature. Past this, there is a tall room full of many crushing things. Make a portal at the very top and jump onto one of the highest crushers. Shoot the other portal through the chain link fence and go through. Jump down with the pneumatic tube (you will be above it, not in it this time). Walk along the tube and jump down to the lower one. Walk into the room with the crusher above your head, and make a portal above it. Then go back and make a portal on the wall that you jumped down from, slightly lower again to account for gravity. Land on the crusher and take it back to the other side. Jump down the hole when you reach it (jump over the railings). Continue on and the crushers will part, dropping you into a room. There are three closed doors that will open; each contains a turret. Neutralize each turret as quickly as possible by either simply sidling up to them or by opening portals behind them. The quicker you do it, the less likely you will be susceptible to being hit. In the third room that opens (with the crane), look up and to the right to see a small crawlspace. Hit the visible part of the wall and then make another portal within reach. Now you will be in a room with semi-activated turrets; these cannot hurt you. Look up through the grating and make a portal, then make another on the wall. Try to land on the pneumatic tube. Jump from the tube to the area above the turret-manufacture area and keep going. You will land behind a turret. Deactivate it. Exit and make a portal on the angled section of the wall, then another on the floor. Loop yourself through until you are on the catwalk. Go forwards.

When you get to a room with a button, press it. A rocket turret will come up. The rocket turret will target you and fire, but it is slow; in most cases, once the target is locked, you can easily dodge the missile and it will blow up whatever else was in its path. The first missile will destroy the glass; walk in front of the other pane of glass and then dodge the rocket. Make a portal in the view of the turret. Do not yet make a second. Advance until you see another pane of glass; place the second turret on the wall facing the glass. Step in front of it and let the rocket lock on, then dodge it. Go through and place the second portal under the tube. Jump over it to get the turret to shoot up at the tube (the angle is a little difficult, so keep trying) and then grab the cube. Go forward and put the cube under the vent to serve as a boost. Walk to the fan, shoot a portal between the blades, and then go back. Make another portal on the floor. Walk through it and you will be in another maintenance tunnel. Ahead there is dangerous water; make a portal on top of the raised metal section to your right, and then make another portal within reach. Walk forward along it.Make another portal across the gap, then one within reach. Go under the grate - marked with an arrow - and shoot a portal up. You will be in a mucky area; shoot a portal up and then another on the wall next to you to get out. However, you will now be in a room full of turret doors opening. Get into one and deactivate the turret, then do the following: shoot a portal on the wall of the room you are in, then shoot another onto the wall of one whose side you can see (like, on the wall left or right of you). Deactivate the turret in the target room. Do this until all the turrets are destroyed. You should end up in the highest area, one of the two with the angled front. Shoot a portal across the way to the lower angular surface, then jump out and drop a portal on your landing location before you hit the ground. While in flight, launch a portal across to the angled surface you were just under (the upper one) and then put another in the path of where you will land. This should launch you across the way to the next section. Walk forward and a crane will drop two turrets. Shoot a portal under each one at a time to knock them down. Then shoot a portal on the ground underneath the opening in the ceiling. Go back out to the tall room and jump out, shooting a portal in front of you before you land. Once you are up (there should be two turbine-like objects that are not moving) shoot a portal on the ground and another on the landing above you. Walk across the catwalk. Walk to the only door with a handle on it and walk forward.

Now you have found GlaDos's core. Wait until the purple core on her falls off. Pick it up, walk over to the control room, and make a portal on the wall. Make another portal near the incinerator (the same one you used to fry the companion cube). Press the button and carry the piece through. Throw it in the fire. After GlaDos turns on the neurotoxin emitters, you will have six minutes to defeat her. A rocket turret will pop up; put a portal at ground level and another above it so that the rocket will go through the lower portal (where you can be a decoy) and end up redirected to hit GlaDos's core. The core piece will end up on a raised section; use portals to get up to it. Burn it up the same way you did the first - make portals from the control button to the incinerator and carry it through. Redirect another rocket at the core; the next piece will end up on the level above you. Make a portal up there and then a portal on ground level; make another portal on the ground after you go through to build up the necessary momentum to launch yourself to it. Grab the core once you are up there, jump down, and go through the steps to burn it. Redirect another rocket; the third core piece will be floating in midair. Make a portal high above it, then another on ground level. Jump out of the portal and get close enough to grab it with the use key (default "e"). Then burn it. Wait for the fireworks and then you will find yourself lifted up. Congratulations! The game is over. Wait for the end credits to roll to hear the final song.

Portal Walkthrough