***Anther’s POV***

Anther reached out and ran his hand along the pretty carvings on the strange door. He tilted his head back and read the words on the plaque above. The boy wasn’t quite sure what to make of the message, but it made it clear that this place was a dungeon. Anther had heard stories of dungeons, though this was his first time seeing one. The image in his head and the scene in front of him were a little difficult to reconcile: carved in large letters on the door was the word “Closed.”

Can dungeons close? Maybe... it’s renovating.

Anther thought that dungeons tried to lure people inside with treasures. He thought that they were able to live because they ate up the people who died inside, or something like that. Wasn’t this dungeon turning away its food? He gave a slight push on the door, just to be sure, but it didn’t open.

“Mn. Because it’s Closed,” he murmured, coming to some kind of understanding.

A funny idea came to him, and he ran his fingers over the carvings again. Carefully, gently, he pressed his fingers into the etchings and tried to move one of the carved tiles. It moved.

“Aha!” Anther’s eyes opened wide, and the corners of his mouth threatened to rise. He turned his head up to look at the plaque again. “You want me to make it Open, right?”

***Archimedes’ POV***

No matter how Archimedes thought about it, the best way to deal with people who couldn’t solve puzzles would be to use traps. Someone who could break down his puzzle door would just break his monsters along with it. However, Archimedes didn’t feel comfortable leaving his safety to something like a trap when there was so little space between his core and the entrance. Someone with an arrow or magic could simply shoot at him from outside as soon as the door was open. His current defenses were one puzzle and a couple of monsters. It seemed to him that the thing to do was provide those monsters a way to grow stronger, and then try to expand his first floor.

There were two ways to grow his monsters stronger. The first way was to deliberately feed them mana, but he would be unable to do other things while he did that. The second was to have them kill things and absorb mana from them. He wasn't about to open his doors wide at this stage, so he would have to offer something from inside the dungeon for them to kill. Archimedes’ plants were… not very efficient for that purpose. It would make much more sense for him to create some animal for them to hunt. If he could make something that would feed on his weeds and reproduce quickly, that would be even better.

Creatures born in the dungeon would gestate and mature to adulthood remarkably quickly due to their nature and the ambient mana, and the weeds would quickly recover as well. It was easy enough to create a self-sustaining hunting environment this way. Technically, dungeon monsters didn’t have to eat, but it would put them into the right mood. The only shortcoming was that a system like that would no longer be enough when he wanted to raise truly strong monsters.

Archimedes didn’t put too much thought into what sort of fodder creature he wanted to make. Rabbits were the first thing that came to mind, and they were good enough, so he just made four of those and set them loose. They were cave rabbits, with soft black and grey fur. He made them lop eared on purpose so they would be more effective prey. For the time being, he ordered the Wolfbats not to attack them.

Fifty-six mana was a big hit for his current self, and Archimedes wanted a lot saved up to be able to expand with. He rested for two days, gathering 960 mana and reaching an accumulation of 25 per hour. Anymore and it would become painful, so he decided to begin his expansion.

The west wall held the path to the entrance. From his remaining three options, Archimedes randomly picked out an area on the north wall, about two meters wide and two meters tall. Gradually, he permeated the dirt with his mana, made the dirt his, and analyzed it. Everywhere there was a mana presence, he erased it. Everywhere there wasn’t a mana presence, he created one. In this way, the material that had been present was canceled out and stopped existing. The region became a mass of neutral territory, which air from the rest of the dungeon naturally flowed into. Archimedes could have replaced the soil with air in one step if he’d wanted to, but why waste the effort when air was going to rush in all on its own?

Actually, it wasn’t just soil that he removed. A few extra things had been mixed in there that he had just gone ahead and erased. Absorbing things left behind in his dungeon and erasing things in order to expand basically produced the same result, which the voice of the world presented to him.

New materials added: asbestos, beryl, granite New creatures added: pill bug, termite

He shooed away the windows as they appeared, focusing on his work instead. By making the walls a little bit rough, he was able to extend the tunnel out to about five meters long. He had waited so long just for this little progress, and now he had no choice but to wait some more.

Archimedes looked to see how his cave rabbit population had grown while he’d been resting. In only two days, they already numbered in the dozens. Truly they had top-notch reproductive capabilities, even for dungeon creatures. In comparison, his weeds were struggling to keep up. All of his other plants and fungi had nearly doubled their area again, and a few mushrooms had fruited from the mycelium. Some of the cave rabbits had taken to eating those when the area around the weeds was too crowded. Archimedes went ahead and sent a message to the Wolfbats that it was fine to eat the rabbits now if they felt like it. To make sure the cave rabbits weren’t wiped out, he warned the Wolfbats to leave at least six alive at any given time. Hopefully they would never get down to six rabbits of a single gender, but it would be an easy fix if they did. He also ordered the monsters not to attack any rabbits that were mating or pregnant. And, while he was at it, he ordered the rabbits to let the weeds grow back if they got too scarce and never to eat them all.

Something like a puzzle, or a trap, or damage to his walls would use the ambient mana to automatically repair itself if there were no invaders nearby, but there was no way something as complex as a living organism would automatically respawn. They could grow and reproduce, but not appear from nothing. Ambient mana simply wasn’t enough, so they would need to use the more concentrated ether to do it instead. In other words, having living things appear out of nowhere would siphon ether away from Archimedes’ control. In the worst case, it would cut off his ability to produce mana. Because of that, the phenomenon was disabled as a default.

There was a practical way to allow creatures to respawn, but Archimedes would have to wait until later before he could use it.

So, his monsters were hunting and he'd dug a short tunnel. Out of the handful of things he was able to do at that moment, Archimedes decided it would be best to move himself out of the direct line of fire, so that at least he couldn’t be seen from the entrance.

A dungeon core could technically be anywhere inside a dungeon. Despite having no limbs, they were able to move autonomously. However, it was safest in the deepest part of the dungeon and it was annoying to move, so plenty of humans seemed to think they were fixed in place or bound to a certain room or some nonsense like that.

It really is annoying to move though.

Archimedes sighed internally and quickly did a few hundred calculations. Without actually spending any mana, he briefly compressed the ambient mana to form something like a wispy pink trail. Like a ball in a trough, his spherical purple core of a body floated along the trail until the end of his net tunnel. A human, of course, wouldn’t be able to see the mana, and would simply think the core was flying.

It was a graceful movement, but it never failed to make him feel sick. Every change in position rendered all of his previous mathematical interpretations of his essential structure obsolete. That image then continued to change even as he redrew it. It was similar to a human feeling dizzy if they watched images that spun around too much.

Expanding his dungeon also changed his essential structure, but that happened so slowly that it didn’t make him dizzy at all. Still, he would rather finish moving quickly than draw out the process and end up doing more work.

It was just after Archimedes had reconciled the various calculations representing his essential structure that something entered his dungeon. It was far sooner than he expected, and he worried about how sparse his defenses were. He immediately began to investigate what exactly had come, hoping it either wasn’t hostile, or couldn’t make it past his puzzle door.

What in the world is that thing?!

However, Archimedes hadn’t expected that the first visitor to his new dungeon would be a creature he had never once encountered before. It was similar to a human, as far as looks went, with a few small differences. The joints had been made more flexible; the eyes had been made more precise; the overall muscular system had been tuned back a bit; and the body chemistry was more similar to a human female, despite the creature possessing a male reproductive system.

These weren’t individual peculiarities. Archimedes knew how to analyze creatures better than they could analyze themselves, and he could easily distinguish which traits were superficial and which were genetically inherited. He could even tell the difference between “family-specific” genes and “race-specific” genes. Physically, this creature was not human.

An intelligent visitor that was neither an outside monster or a human… Archimedes had no idea what to expect from him. He was somewhat afraid of this stranger, and his odd mana structure did nothing to help that. The way that mana interacted with the creature’s body, as if the passive thing called mana enjoyed his company was unsettling. Was this thing a mortal or wasn’t it? It seemed to be, well, somewhere in between, and that was bizarre.

Probing this creature made Archimedes uncomfortable. Until he could figure out the best way to circumnavigate the strange effect it had on his mana, he would rather avoid probing with it; it was dizzying.

Archimedes continued to warily watch the creature using basic visual information. It had long and soft brown hair that was loosely tied back, slightly tanned olive skin, round, vibrant green eyes, and ears that came to elongated points. Except for the ears, Archimedes had seen humans with all of those qualities, so he decided to call this creature a long ear for now.

The long ear boy kept touching his puzzle door curiously. Archimedes kept quietly hoping for him to walk away without realizing the puzzle that was there. However, the long ear realized that the tiles could be moved, and an inspired light filled his eyes. He looked up at Archimedes’ plaque as if he thought that that was where he was watching from.

“You want me to make it Open, right?” the boy guessed, eyes glittering.

I would rather you didn’t, Archimedes worried. The temperature in the dungeon started to subtly decrease, but the long ear just started to hum some tune without minding it. He started to move the tiles around and soon one clicked into place.

“Hum?” The long ear tugged at the fixed tile, realized it was stuck, and looked worried. “I… didn’t think they would get stuck.” His eyes darted back and forth nervously as he examined the other tiles. Finally, he picked another one that he wanted to move, but it got stuck in place almost immediately, one space away from the previous tile.

“Ah! No! Not there!” The long ear ran his hands through his hair in frustration. He fidgeted in place while wringing an unstrung shortbow in his hands. “No, that’s,” he looked apologetically up at Archimedes’ plaque, “Can I… try again?”

Of course, Archimedes didn’t respond. If he were a human, he’d be holding his breath with how nervous he was. Please go away, little boy.

The long ear hung around a minute longer before sighing and turning around. He stepped outside of the dungeon entrance and Archimedes felt a wave of relief wash over him. The dungeon temperature promptly returned to normal as well. However, he heard a small click ring out, and immediately tensed up again. The puzzle was resetting itself since there was no one in its range. To Archimedes’ despair, he saw the long ear boy stop his feet, and his ears twitched at the sound. He looked back over with round and innocent eyes and clearly saw that the sliding puzzle was resetting itself.

A grin appeared on the boy’s face, and he trotted back into the tunnel. The puzzle stopped moving, despite clearly being incomplete, and the long ear tilted his head. Looking down at his feet, he saw where the mountain grass ended and took a step back. The puzzle resumed repairing itself.

“So… you can’t do it… when I’m inside?” The long ear tilted his head, “Or… are you shy?”

Archimedes groaned inaudibly, but the long ear boy was completely ignorant. He waited for the puzzle to finish resetting then trotted back up to try again. Soon he ended up in the same situation as before, and he gave a dissatisfied huff.

“Um... this is pretty hard.” The boy looked up at the plaque again, rereading the message that said “Brutes and fools beware: this dungeon calls for a sage.” His eyes hung on the words for a few breaths. Finally, he gathered up his things and trotted off, but Archimedes didn’t exactly feel pleased about it. That long ear child was going to bring more people here for sure, wasn’t he? They could break through his first puzzle with trial and error if they were patient enough.

Besides that, did that boy have a verbal tic? Why did he keep trailing off in the middle of his speech? My ability to process sound isn't damaged, is it?

There were a lot of things to think about all of a sudden, at various levels of importance.

The chances now were high that more people, or at least more long ears, would start to visit his dungeon. Through trial and error, they would soon crack his first puzzle, and then what would he do? Feed them treasure and beg them to go away? It would be absurd to make a dungeon for attracting the clever only to kill them for clearing it fairly.

There was another problem Archimedes had only just thought of. What would he do if people started to record the answers to his puzzles? Even a complete meathead would be able to pass through if they knew the correct answers ahead of time.

There were only two ways for a dungeon core to survive once they became known. First, was to be unbeatable. If nobody could reach the core, then they couldn't capture or destroy it either. This was the method Archimedes had used in his past life. It was slowly dawning on him that there was no way he could repeat that accomplishment with only puzzles to hold people back.

The second way was to be worth more alive and free than dead or enslaved. Producing rare and useful things would be expensive. Having frequent visitors to his dungeon would be risky and stressful. Archimedes couldn't think of any other way to protect himself and accomplish his goal.

Archimedes knew what sorts of things humans liked, but long ears might not like them as well. Luckily, the only long ear he had seen had not come empty handed. Wild game, herbs, and ranged weapons: he thought these things might be seen as suitable rewards.

Archimedes ordered his Wolfbats to move into the only completed room. He would allow those who solved his door puzzle to loot the first hallway. They could hunt his cave rabbits or harvest his plants and fungi as they liked.

He should probably plant something actually useful since it was supposed to be a reward. The blue flowers the long ear boy had been carrying could be used to produce a mild medicine for headaches, but it was also a natural sweetener. Would the long ears prefer cooking herbs or medicinal herbs?

Cooking herbs were cheaper, so he would start with those. Archimedes used the mana he had slowly gathered to create a black pepper plant and a patch of red flowers with very sweet blossoms. Hopefully at least one of them would suit their tastes. He had to wait a while before he could then create a patch of ice ferns: light blue ferns with small, delicate leaves. They could be used in medicine to ease fevers.

That should be enough for a single-floor dungeon, right? With that much, they should think that they stand to gain the most if they let me grow.

Archimedes tried to convince himself that this much would be fine and decided that he ought to have something separating the room where his Wolfbats were from the room the invaders were allowed to plunder. It would be bad if his monsters were attacked along with the rabbits. For that reason he started to think of challenging puzzles while waiting for his mana to accumulate.