Portal 3 has 12 chapters.

Chapter 1: Introduction

Chapter 2: The Repair

Chapter 3: Taylor

Chapter 4: The Rat

Chapter 5: The Bad Chambers

Chapter 6: The Turret Complex

Chapter 7a: Neurotoxin Pt. 1

Chapter 7b: Adventure

Chapter 7c: Neurotoxin Pt. 2

Chapter 8: Guards

Chapter 9: Gathering Pieces

Chapter 10: Military Chambers

Chapter 11: GLaDOS 2.0

Chapter 12: Ditto Gel


The game starts off as your player, who you later learn is a clone of Chell, awakes from the bed in a Relaxation Vault. The scene around her is extremely similar to the first game, but the clipboard is on the floor, the cup is shattered, and the radio is gone altogether. This is a reference to what players usually do upon starting gameplay of the first Portal game. Several seconds after you get out of bed, the intercom comes on, but only static is heard. Then a portal opens. Once you walk through and go through the door in front of you, a small robot jumps down form the ceiling and introduces herself as GaTIC. GaTIC says that she is a temporary replacement to GLaDOS. You complete the first test chamber, which is exactly the same as the first test chamber in the first Portal game. But for some reason, the ceiling is missing, completely ruining the image that it is the first game. After you complete the chamber, you move on into the chamberlock, and the elevator. The elevator moves down into the next chamber, which appears to be unfinished.

There is a long catwalk, with views into test chambers that give you a sneak peek into later testing elements, but if you try to jump off the catwalk, you die. GaTIC leads you to another room. The intercom once again comes on, but again there is static. Then you are introduced to portals, in a test not similar to the one from Portal 1, but serves the same purpose. Then a panel falls off before you enter the elevator, flustering GaTIC. You enter the panel and take the Portal Gun. GaTIC says not to shoot the Portal on the ceiling over there, so of course you do. Then you enter the Orange Portal and come out in a new area.

GaTIC is still extremely flustered, saying that you never went through the decontamination process. Then she recovers herself and introduces you to Propulsion Gel. After you complete the puzzle, you are presented with the Portal Gun Upgrade. Then you go once again into the chamberlock. But the elevator stops to a halt and opens. You have to crouch to get through, but you come out in a room with Energy Pellets. GaTIC is extremely flustered this time, and says that they never wanted to use the energy pellets again. But then she lets you continue on with the test. Then, after you have completed the test, you start to go into the elevator, but GaTIC stops you. She says that the elevators must be malfunctioning, and that you should follow her. You walk down a long catwalk with stairs, and you finally come out in a room with Discouragement Beams. You are also introduced to Discouragement Redirection Cubes. Then after you complete the first part, an Unstationary Platform takes you to the second part, which introduces you to Discouragement Relays, as well as Reflection Gel.

Then after that test is completed, you are commended by GaTIC, and she asks you to help repair GLaDOS, as she should have come back online by now. You follow GaTIC down a passage that leads to a room with tons of cores attached to bodies aimlessly ambling around, bumping into walls. GaTIC says that these robots were supposed to have fixed GLaDOS by now, and she tells you to escort the defective bots to the Incinerator. You have to keep the robots from getting themselves stuck in the air vents. Out of a total of 24 bots, at least 8 must survive. If you get all of the bots to the incinerator(which is extremely hard), you are rewarded with an achievement, as well as the ability to allow one to survive, because GaTIC says that this one might be helpful. Then you and the bot are taken to GLaDOS' Chamber via Instant Relocation Panel. You then have to reconnect a ton of wires, to the bot, to GLaDOS, and to a generator. Once you complete it, you need to attach a jumper cable, and then it works. Then GaTIC escorts you to the chamberlock, saying GLaDOS will greet you shortly. You decide to sleep on the floor of the elevator. Then you awake to the annoying voice of GLaDOS. She tells you to go out of the door and into the chamber. She says you have a new friend. Another elevator opens up, and a man walks out.

The man introduces himself as Taylor. He says that he was an orphan adopted by Aperture Science. This chamber introduces the new game mechanic of commanding Taylor to pick up and move objects. Then, after you have completed the chamber, GLaDOS tells you to go down a newly opened door. This chamber introduces you to Repulsion Gel, but also to using gels with Taylor. After this chamber is completed, you move on to another one. GLaDOS says that you will temporarily have to solve the puzzles without Taylor, and he'll be going through the same tests. In the next chamber, you are introduced to Sentry Turrets. It is an extremely long level, seeing as GLaDOS continually lengthens it. After about 12 times of GLaDOS lengthening the level, she finally lets you finish. Then Taylor comes back and says that the whole reason it took so long was because he was terrified of turrets. Then in the next chamber, you must use Edgeless Safety Cubes.

After that is completed, you are escorted into another chamber, but halfway through, something glitches. A hole opens up in the floor, and you and Taylor run for it. It takes you to some unfinished chambers. GLaDOS doesn't object to your being there, because you couldn't possibly escape, and you "might as well solve the test chambers while you're there". So you have to solve several test chambers with only half-finished aspects and several turrets(which Taylor won't help you with). After 25 different test chambers with strange unfinished parts, GLaDOS takes you back up to a chamber where she says you need to "kill the rat." It turns out that she was talking about Doug Rattmann. He offers to help you escape if you let him live. Apparently Doug Rattmann was employed by Aperture Science 2.0. So a panel opens, and you gain a third team member. The three of you drop down into an odd room with a snarling noise echoing in every direction. Rattmann tells you that it's from an abandoned Anger Core 2.0. The Anger Core sends TAFRs after you to attack you throughout all 40 levels inside these chambers. Eventualy you have to battle the core, with it constantly sending TAFRs and has anger gas, which severely debilitates your accuracy and speed. Rattmann tells you that there will be plenty of cores to deal with later. After, he tells you to go into the tubes of the facility, but GLaDOS takes over and splits you and Taylor up once again. Now you have to solve 56 chambers without Taylor's help, and 23 with, with GLaDOS changing it every now and again. On the next chamber, Rattmann again tries to help you escape.

He takes you to a door that leads to chambers with malfunctioning cues and insanely moving parts. Here you are introduced to Plasmatic Spheres, as well as Magnets. There are also defective versions of many testing elements, such as Defective Turrets, Defective Excursion Funnels, and Defective Unstationary Platforms. Once you have completed about 25, a malfunction again seperates you, and sends you to an odd place with Rocket Turrets and many other turrets. Plasmatic Spheres are also here. After you complete 60 levels of this Turret hell, you are again allowed to do chambers with Taylor. After 24 chambers in this manner, GLaDOS says that you must fight Taylor. This battle is rather unfair, because you cannot surrender, and you will die, but if you defeat Taylor, he surrenders. GLaDOS says that you cannot do that, and that she will execute Taylor and you with neurotoxin. Then Rattmann intervenes again, and he helps you complete the test chamber before you die from the neurotoxin. In this part, it is revealed that your character is a Chell clone, as GLaDOS says you are expendable, and there are many more of you. Once you complete this chamber, Rattmann tells you that while you are a clone, you are the last one, which GLaDOS doesn't realize. He also tells you to find the original Adventure Core, which will help you find and disable the Neurotoxin processing center.

He says that the Adventure Core should be in the Adventure Chambers, and he sends you down a tube that leads to the chambers. You and Taylor must complete 5 very hard test chambers here, and proceed to do a complex flinging operation to reach the Adventure Core in the 6th chamber. Once you get him, you tell him that you need help disabling the Neurotoxin, and he escorts you to the area. He then tells you that you need a Disabling Rod before you can destroy the Neurotoxin generator. He also says that the Disabling Rods are located in Office 732, and that he will rig the Instant Relocation Panel to take you there. The Instant Relocation Panel takes you to the beginning of the area, and you must hunt your way through trash-filled areas with a bunch of turrets to get the Disabling Rod. Once you have it, you return to the Relocation Panel, and realize that it has been turned offline.

So you must look for a way out. You find one at the end of the office area; a broken window overlooking a test chamber is there. You go back into the test chambers, and GLaDOS keeps trying to reach these long-disabled chambers, but fails. After 9 of these chambers, Rattmann returns and helps you get back to the Neurotoxin Center. You must go through the Offices, and disable 12 hoses first. This consumes quite a lot of time. Once you have completed this task, Mobile Turrets go after you. You must now go to Hallway 17K and get to the elevator, and go down. Once at your destination(the floor beneath the Neurotoxin Center), you must destroy 5 binders, all while avoiding Mobile Turrets. Once that is complete, you must retrieve a bomb from a test chamber, without it exploding, and bring it to the top of the Neurotoxin Tank, and let it explode.

Then Rattmann comes and gets you again, and takes you to an Office. He tells you some information on how to get to GLaDOS' Chamber to defeat her. He says that he will rejoin you at the Recycling Center, which contains a helpful tool to defeat GLaDOS. But first, you must retrieve some information from the Intelligence Core. So you and Taylor go to Office 781 to find the papers containing the location of the Intelligence Core. Here you are introduced to Guards. Once you retrieve the information, you escape to Rattmann's main den. The information says that the Intelligence Core is kept in Storage Chamber 42-50A-19.

Taylor realizes that you need to get a map of the facility. You and Taylor go on a hunt throughout Rattmann's main den to find it, while unearthing odd testing elements and items. Once you find it, you read it and follow the instructions. You go along a complicated path, fighting Guards, all the way to an Instant Relocation Panel. You go through the panel and into Storage Wing 42-50, on floor H. You make your way down to floor A, and then find chamber 19. Once you find it, you extract the information from the core, destroying it. You return to Rattmann's lair, and he is there, saying that you must destroy the Guard Manufacturing Center before it becomes impossible to maneuver throughout the facility.

You head to the Manufacturing Center, and you must disable 12 wires for 6 different areas, while avoiding many Guards. Then the Guards start to repair the facility, so you have to go and destroy more parts to slow them down. Afterwards, you again return to Rattmann's Den, where Rattmann tells you to go to the Recycling Center, finally.

You head to another IRP, and it takes you to the first area of the Recycling Center, an area with many crushers. You must evade the crushers to find several pieces of Rattmann's tool to defeat GLaDOS. Afterwards, you move to the second level, where there are Flame Tubes. You again must dodge this hazard and find more pieces. Then you move to the next level, where the molten metal is being cooled. There are several more pieces here. Once you have all the pieces, Rattmann assembles the thing, what he calls a Disruptor Block. He says that you must use it to disable GLaDOS' shielding system. You and Taylor go down a long path towards the Shield Unit. But halfway, you are trapped by GLaDOS, and put into a series of 40 "Military Chambers" with many turrets. Once you complete these, you continue on to the Shield Unit.

Once there, you must set up the Disruptor Block while avoiding Guards, and connect three wires to it. When completed, something glitches, however, and the Block stops halfway. Then a ton of Guards converge, and you must run for it. You run back to Rattmann's lair, and he takes you to the IRP that will transport you to GLaDOS' Chamber.

You arrive there, but GLaDOS diverts Rattmann and Taylor away, and only you are remaining. GLaDOS obviously didn't mean to do this, and instantly begins attacking. This battle may take a while, as there is no one telling you what to do, but if 15 minutes pass, and you haven't figured it out, it does the first one for you. What you must do is make a Bomb collide with a rocket in front of GLaDOS. You must do this several times, and each time, a new complication is added. Once you finish that, the shield fails, and the next time the bomb and rocket collide, it knocks out one of GLaDOS' Cores. The first core that it knocks out is the Curiosity Core 3.0. This Core is the same as the original Curiosity Core, except with a different voice, and a couple new lines. You must do the collision thing, but with the core to destroy it. Then you must again collide them in front of GLaDOS, giving you the Anger Core 3.0. This core is exactly the same as the Anger Core at first, but it's growls and snarls get much more intense. Once you have destroyed it, the next core is the Rocket Core. Once you destroy it, the rockets stop firing, so you must now bombard GLaDOS with bombs. The next core is the Survaillance Core, which creepily looks at you. Once you destroy it, the final core is the Bomb Core. Once you destroy it, the bombs stop, so you cannot harm GLaDOS anymore.

Luckily, Rattmann and Taylor come to the chamber, and Rattmann tells you to use this, something he built. You use the odd tool, and it disintegrates GLaDOS. Rattmann tells you that the object will now explode, so you run for it to an IRP. You get on it and teleport away, and, on the other side, the panel goes dark, meaning that the other one was destroyed. Rattmann tells you that they can escape now, and that they should head to Hatch 5. Once there, Rattmann presses the button, and nothing happens.

He says that that is a terrible thing, and it means that there was a backup GLaDOS, or something. So, at Rattmann's instructions, you head to the Archive Center. There, Rattmann goes through a bunch of files. He finds the one that he was looking for, but the information is the same. He says there can't be an explanation, except..., and trails off. Then he tells you to follow him. You go to the Gel Manufacturing System. There there is all kinds of gels, as well as a new testing element, a Gelbot. Gelbots are not used in any test chambers in this game, but they are often used in custom maps. Rattmann tells you to find any gel that looks out of place. You search the facility, but only find minute amounts. Rattmann then tells you to follow him again.

This time you go to the Goo Sewers, which is exactly what it sounds like. There you continue looking, while fighting off Guards, and find more. Rattmann and you and Taylor travel off to the Tubing System, where quite a few complex puzzles must be solved. This al takes place while following the trail of the odd Gel. You follow it to the final chamber of the game, the Ditto Chamber.

Rattmann tells you that this intelligent Gel has taken control of the facility, and you must destroy it. (Boss battle coming soon)

After you have defeated the gel, something explodes, sending the three of you flying. You land on the ground, and as you fall unconscious, three cores with bodies(Space Core, Adventure Core, and Wheatley) fly off with one of you. Then the ending song(s) play.


Fans of the Portal franchise received the game very well. It was a much loved game, and "is exponentially better than Portal 2 even more than Portal 2 was better than the first game," according to one fan. Several people complained about the price but it was agreed that the game was worth it's high price. The game was temporarily available half-price for the anniversary of Portal.