Just a random idea I had...
"Congratulations. The test is now over."
She could not believe her ears. She had flirted with death for hours on end, hurtling over pits of acid and dodging bullets of rather talkative turrets. No matter, she was done. And she knew that just around the corner would be a delicious cake. As the platform rounded the turn, she was greeted with a room full of fire. She started to panic as the scaffold inched closer and closer to the blaze.
"All Aperture technologies remain safely operational up to 4000 degrees Kelvin. Rest assured that there is absolutely no chance of a dangerous equipment malfunction prior to your victory candescence. Thank you for participating in this Aperture Science computer-aided enrichment activity. Goodbye."
Goodbye? Oh god, she's going to bake me, isn't she? Chell thought to herself. She's going to bake me and I'll never see the light of day again and the sweet taste of buttercream frosting will never touch my tongue. The platform confirmed her suspicions as it began to descend lower into the the fire. She shut her eyes as her skin began to dry out. Suddenly, the platform stopped.
"Well, it looks like you've come upon a rare streak of good fortune." The computer spoke through discrete speakers placed about the room.
"Huh?" Chell wondered out loud.
"I have just been notified that the remodeling of our formerly-destroyed test chamber 20 has been completed. You will be the first to attempt to pass through it in over four decades. Company policy states that purposeful and unavoidable murder is not allowed before all chambers have been completed. And fortunately for you, construction of our state-of-the-art Aperture Science Anti-Oxygen Subject Asphyxiation Zone at the end of test chamber 20 is still under construction. Rerouting Unstationary Scaffold in three...two...one."
The platform rose out of reach of the flailing tongues of fire. It began to move backwards into test chamber 19. However, a wall had opened up to reveal a platform with an elevator behind it. The scaffold stopped at the platform and Chell quickly leaped off, glad to have survived once more. The doors to the elevator slid open.
Chell stepped in and was overcome with a smell of sulfur mixed with electrical fire fumes. The elevator doors slid shut and descended further underground.
–
"Welcome to the true final test. When you are done, you will drop the device in the Equipment Recovery Annex. Enrichment Center Regulations require both hands to be empty before any cake can be served."
You said that already, Chell thought. She stepped out of the elevator and waited for the hazard sign to flicker to life. It stayed dark. They must not have done a good job fixing the place up, Chell thought. She found herself in a room with nearly the same dimensions on all sides, ten meters by ten meters by ten meters. In the very center of the floor was a small hole, and in one corner was an Aperture Emergency Intelligence Incinerator.
Where's the elevator? Chell wondered.
"You will follow directions exactly as I say or we will bake you a sugar-free cake. Without cherries or chocolate. We might just give you rice cakes."
Chell listened intently.
"You will drop the device into the Emergency Intelligence Incinerator within twenty seconds."
The incinerator opened and hot air rushed out. Chell did not hesitate as she threw her portal gun into the molten metal below.
"Well done. The incinerator will close in three...two...one." The incinerator closed.
"You will pick up your new device from the delivery apparatus in the center of the chamber within twenty seconds."
Out of the hole in the center rose another portal gun which looked exactly the same as her old one. Chell picked it up and noticed a three-way switch on the left side of the trigger with three positions: Neutral, One, and Two. The switch was set to Two. Another switch on the other side of the trigger had two positions: Mode 1 and Mode 2.
"We have been improving upon this prototype for the last four decades. With mode number one, the device is able to create three linked portals at once, with a switch to choose the portal from which you will emerge.
Chell couldn't stop herself from smiling. One entrance and two possible exits? It was nothing short of amazing. GLaDOS continued to explain the new features.
"When switched to Mode 2, the device will still be able to fire three portals, but it will also be able to fire portals through other portals. The device is now waterproof up to 30 meters and it is safe to look at the operational end of the device for less than two point seven seconds. It is resistant to up to fifty thousand newtons of force and it can be powered with a solar battery. It also is now compliant with some to most of the regulations set forth by the American Portal Science Society."
"What do you want me to do, though?" Chell asked.
"Very simple. Test the effectiveness of the Portal Selector Switch to the left of the trigger. Make sure the device is set to Mode 1. Please fire your first portal directly in front of you, your second portal to the left of your first, and your third portal to the right of your first. For optimal results, leave one foot between the portals and wait three seconds between shots."
Chell complied, attempting be as precise as possible. Wow, this thing has a kick. She marveled at the new prototype.
The portals were now colored green, orange and purple, and only the center and right portals could be seen through.
"Manipulate the portal selector switch so that it is in the 'One' position." Once Chell flipped the switch, the rightmost portal became opaque while the leftmost one became see-through. "Please step through either transparent portal." GLaDOS instructed. Chell stepped through the center portal and emerged from her left portal.
"So far you are doing excellent work. Before we continue, I am pleased to present to you another amusing fact. This device has been voted to be fifty-four times more dangerous than a pride of starving lions on steroids."
Good to know, Chell thought.
"Now manipulate the switch so that it is in the 'Two' position and step through either of the transparent portals."
As expected, Chell entered her central portal and emerged from the rightmost portal.
"Excellent work. Now set the switch in the 'Neutral' position and step through the translucent portal."
Chell did as she was told. Now the two side portals were opaque and the center one was just barely translucent. She stepped through the central portal but was shoved back out by an unknown force.
"Excellent. Mode 1 has proven to be flawless. Now change the device to Mode 2. All extant portals will be dissolved."
Once Chell had done so, GLaDOS offered another "amusing fact". "The device in its current state has been declared in Time Magazine to be 'The Harbinger of The Apocalypse'. It, however, is not hazardous to the outside world due to a thicker lead shield around this chamber."
"So what do I do now?" Chell asked as she changed the mode with a shaking hand.
"Simple. Fire one portal in front of you, and one behind you." Chell did as she was told. "Now fire a portal through the one in front of you so that it emerges from the portal behind you and creates a third portal next to your first portal."
Chell thought for a moment and did as she was told. The prototype successfully fired a portal through a portal.
"Excellent work. There is one last task before the Cake Escort Team brings you your cake."
"What is it? TELL ME!"
"Switch to Mode 1 and back to Mode 2 to dissolve all extant portals." Chell successfully complied. "Now fire a portal in front of you, one behind you, and fire the third through the first such that the shot will go through the portals infinitely." Chell aimed into the first portal and fired. At least, she tried to. The device made an odd clicking noise and began to warm up.
"Oh, dear. It appears the issue has not yet been fixed. Goodbye and thank you for your commitment to science."
Goodbye? Oh god, it's going to blow up, isn't it? Chell thought with horror. The device confirmed her suspicions as it did just that.
–
"Attention, Test Chamber 20 Improvement Team. Your expertise is required once again. Also, bring a mop."