Prisoner's Dilemma
“This looks like a classic Prisoner's Dilemma.”
The 7th floor, arrived at once more after dying and dying again — roughly six times this go-around.
“Everything comes in matching pairs. Even the shopping carts come in twos.”
This time, instead of a polling station set up in the auditorium, it was a checkout counter set up in the market.
Two checkout counters would serve as ballot boxes, and the massive partition wall standing between them would play the role of the voting booth.
“They look like bags of snacks…… but there's nothing written on them. No images either.”
“The labels will appear once the dilemma begins.”
A shopping cart holding a single product with a completely blank wrapper — that would be the ballot.
The choices themselves would probably be different from last time, too.
This constant shifting of the stage and the options was the defining trait of the Prisoner's Dilemma labyrinth.
“……”
So who would be solving this dilemma, and with whom?
I turned back with my one remaining eye and looked over the three of us who had survived this far.
Yu Hyeonjae. Lee Jinsu. Jeong Jiho.
Lee Nahyeon, Choi Jaeha, and Hwang Juyeon had died back on B3, offering themselves up as spare parts for the headless horseman.
This was the first time I'd ever reached the 7th floor with my body intact.
“U-um…… excuse me……”
“Lee Jinsu? If you need anything, please say so. You mustn't force yourself to get up.”
Lee Jinsu, who had lost his right arm last round, had — remarkably — survived this time.
Though he was in such a state that the slightest touch might send him toppling over, dead on the spot.
“Could…… I do it……?”
“I'm sorry? Do what…… oh, the Prisoner's Dilemma.”
It was good that a volunteer had stepped forward, but.
“Lee Jinsu.”
I lowered my voice to a whisper.
There was something I needed to confirm.
“Do you want to die comfortably, or do you want to live comfortably?”
Jinsu was someone who couldn't tell those two apart — and that was exactly what made him such an unreliable partner for the Prisoner's Dilemma.
“……”
If he wanted to die comfortably, there was no way I could let him go through with it.
Suppose he was in agony right now, physically and mentally, desperate to end it — but then the labyrinth offered him a choice that promised to erase all of that pain?
How would anyone know what he'd pick?
The heart is a fickle thing. Different going in, different coming out.
“I……”
Jinsu stammered, mouth opening and closing as if the words had jammed in his throat, and looked away from my single eye.
“I want…… to live…….”
He let the sentence trail off, as if admitting it were something to be ashamed of.
And that's how I knew he meant it.
The will to live — and the shame of only now, after everything, wanting to live. Both of them.
“Then may I do it instead? With you, I mean.”
Yu Hyeonjae had volunteered out of nowhere.
“……I appreciate the offer, but.”
What was he playing at?
“I'm the right person for this. I'm the one here who can most afford to absorb a loss.”
He wasn't wrong.
I'd lost an eye in Happyland. Jinsu was missing an arm and hovering half-dead. And Jeong Jiho was all of seven years old.
“Lee Jinsu.”
The co-CEO of Yuwi Guild, seated on the floor as if kneeling, gently wrapped his hand around the employee's left hand and looked him straight in the eye.
“As long as it doesn't cost me my life, I am willing to accept twice the loss. So choose the best option available. Pay no mind to me.”
A mind-boggling thing to say.
Made worse by the fact that he seemed to mean it.
“You…… you really mean that……?”
“I do. Truly. Why else would I go to the trouble of telling you all this in advance?”
And so the dazed Lee Jinsu and the impassive Yu Hyeonjae parted at the partition wall, each examining their pair of shopping carts.
Crinkle.
Something seemed to be inscribed on the plastic wrapping of the goods inside — both men read the contents carefully, faces grave.
“……”
I watched the two of them together with Jeong Jiho.
Tap.
Hyeonjae picked a cart first and set it on the counter.
A quick choice, as if he hadn't agonized over it at all.
Beyond the partition, Jinsu flinched at the sound.
Tap.
It was a long while before Jinsu finally placed his cart on the counter.
Had they tried not to pick the same option, without coordinating beforehand?
Except that didn't seem to be it — they appeared to have chosen different options.
One had taken the left cart, the other the right.
「Beginning gift checkout.」
Gift?
Ziiiing…….
The rails on both checkout counters began to move.
Beep. Beep.
As the carts reached the scanner at the end of the counter, the barcode-verification chime rang out.
「Gift checkout complete.」
Jinsu and Hyeonjae remained standing on either side of the partition, waiting for the results.
「Printing gift purchase record.」
Gift.
A gift meant something you gave to someone else — not to yourself.
Which meant…….
the choice might not even apply to the buyer at all.
“……”
Then it made sense.
Why Hyeonjae's choice had been so swift, and why Jinsu's had taken so long.
「Item No. 1: ‘Glass powder, 30 grams — for feeding in one bite to a friend only.’」
Glass powder, thirty grams?
That was enough to fill an entire rice soup bowl to the brim.
I didn't know the exact lethal dose, but swallowing that much in one go wasn't going to end well for anyone.
And if it doubled to sixty — death, guaranteed.
「Quantity: 1.」
“Ha—”
A huge, shuddering gasp tore out of Lee Jinsu, as if he might suffocate on the spot.
A sound tangled up of relief and lament.
「Item No. 2: ‘Glass powder, 30 grams — for feeding in one bite to a total stranger only.’」
「Quantity: 1.」
That would have been the kinder option.
Ordinarily, killing a stranger beats killing a friend.
「Executing gift purchase results.」
「Buyer ‘Yu Hyeonjae’ has had 60 grams of glass powder fed to his friend.」
“……”
I had no idea who that friend was, but I sincerely hoped it was instantaneous. As painless as possible.
“S-sir…… CEO…… thank— no, I'm…… I'm sorry…… truly……”
“Ah…… I did promise. Rather than thank me, perhaps you'd join me in a prayer for their soul…….”
I had plenty to say about that abominable conduct of his, but I decided against saying any of it.
「Buyer ‘Lee Jinsu’ has had 15 grams of glass powder fed to a total stranger.」
Fifteen grams, I wasn't sure about.
Would they survive if they got to an emergency room right away?
Whoever it was, I hoped they were someone outside the labyrinth.
“Still, it would've been nicer if one of your options had been fixing your arm, Lee Jinsu.”
“Ah, um…… yeah, I guess so……”
This dilemma alone seemed to have hollowed Jinsu out completely; by now he looked like none of it mattered to him anymore.
And honestly, whether his arm was restored or not, it wasn't a particularly important thing.
“Let's rest a little longer, then head down.”
Not that it mattered much. Every one of us would most likely die on the next floor anyway.
B2 Mechanical Room.
Drip. Drip. The sound of falling water.
Vrooom, thud-thud. The chorus of enormous machinery, vibrating as one.
Tap, tap-tap. Four human beings splitting off in three directions, picking their way carefully between the pipes.
Barely relying on the glow of our phones, we combed the mechanical room inch by inch.
Metal vines embroidering the ceiling like a maze, metal stalks thrusting up from the floor.
There was a bleak, desolate beauty to this forest of machines.
BANG—!
Suddenly, from the darkness far away — the sound of a hot water pump bursting.
Sploosh, rush-roar…….
The sound of death rising fast, from the ground up past our feet.
“Over here! Over here!”
“So it burst in a spot where we weren't. Again.”
Gathered or scattered, the sabotage only ever picked places where no people were. Every single time.
“One rule at least seems certain. It will only detonate outside our line of sight. Without exception.”
“Then…… what do we do……? Four people just isn't enough to cover a space this big……”
We'd need what, thirty-odd people, maybe more?
“Then again, perhaps it isn't a matter of numbers at all.”
I thought so too.
It was obvious the labyrinth had no conscience, but even so, it never posed an impossible problem.
And hauling more than thirty people into the mechanical room was an impossible problem.
Come to think of it, it was questionable whether this place had even thirty people to begin with, back when the labyrinthification started and the building's occupants were split up and relocated like an instance dungeon.
“I suspect there's a way to solve this even with too few people. If only we knew the rules in more detail……”
“Then we'd best not waste time.”
Slosh.
Hyeonjae, holding Jeong Jiho in his arms, lifted one leg out of the water and set it back down.
The water had already swallowed our ankles and climbed past our calves.
Soon even proper walking would become difficult.
“At this rate…… forty minutes, at most, I'd say.”
Which meant in forty minutes, all of us would drown together.
“……”
In a silence heavy as the open sea, I quietly studied my ragtag little band — the tall, the small, and everything between.
I had died in all sorts of ways, and drowning was among the worst of them.
“You remember the rule about the emergency stairwell, don't you? Stand still for more than five seconds and the floor gives out.”
“……Pardon?”
These people had no need to suffer that kind of agony.
If they had to die anyway — didn't they deserve, at the very least, a slightly less painful death?
“Once the water rises past my knees, we could all pile onto the emergency exit and it still wouldn't open. The water pressure.”
“What are you suddenly——”
Lee Jinsu frowned, bewildered, and then went silent.
He'd understood what I meant.
“Whatever's waiting at the bottom of those stairs — I'd wager it's better than drowning.”
On that much, I could promise.
“But…… why are you giving up already……? There's still more we can……”
“Pardon? I'm not giving up anything.”
It was unlikely we'd clear this floor in one go, of course.
I'd love to be wrong about that.
Which was exactly why, if I died, I had to die having gathered as much information as possible.
Fleeing to the emergency stairwell would accomplish nothing.
“If I die, I die here. I'm telling you that up front, so you can make your choice with eyes open.”
Jinsu's face twisted into confusion.
As if he couldn't tell whether to be angry or dumbfounded — couldn't even figure out what he was supposed to feel.
“Th-then…… me too, I'll…… think about it here, a little longer…… I want to.”
“……Good. Then let's puzzle it out together while we do. How we might get out of here.”
I didn't dislike people who fought to stay alive in the face of a terrible death.
CRACK—!
Another pipe burst somewhere, once again.
And of course — from a place our eyes couldn't reach.
“It really does seem to be picking fights with us on purpose……”
“Could it be an intelligent monster, I wonder? Not some formless phenomenon?”
“That's possible, I suppose. Hiding in the shadows, or perhaps——”
“—Ah!”
Jinsu's shout burst out abruptly, cutting Hyeonjae off.
“What is it? Are you all right?”
I assumed the pain from his arm had flared up.
But that wasn't it.
“What if…… what if it's not that? The monster — or the phenomenon, whatever it is — what if it's not just toying with us for spite…….”
Jinsu looked straight at me as he spoke.
Or rather — straight at the empty socket where I'd lost my right eye in Happyland.
“What if it's avoiding us?”