The question was, obviously, where to start.

It looked at its lower floors: 50, a sprawling cavern dotted with groves of luminous fungus, featuring a whole secondary section in honeycombed caverns along the ceiling, lit by glowrock outcroppings embedded in the cavern roof; and the 51st, a barren expanse of bare rock that it hadn't gotten around to doing anything with yet. Its core, a person-sized chunk of faceted crystal, was seated within a cave region on the unfinished floor 50, mostly just to move it away from the boss room on floor 49.

Before all of this, it had been considering starting up something with lava, maybe? The fungal cavern theme had run its course, it had thought. This deep down, the chill of the caves had turned into a gentle warmth, and it had started to place down pyrofungus around seams of heat as it exposed them in its constant digging. Their gills gleamed red among the cavern floors, glowing more and more intensely until they were fierce yellow-white beacons, rippling the air around them with heat. Then they erupted in a ferocious storm of superheated spores.

Previously, it had considered them a clever hybrid between a timed trap and a fungus. Now it was just more artifice. Why did they exist? Because it had been thinking about lava. Why superheated spores? It had the suggestion of a reproductive cycle, but... like everything else in its corridors, it only existed because it wanted them to exist. Because of "theme". It had bothered to make them reproductively viable, but in practice the fledgling pyrofungi were torn apart by the blasts of their more mature parents; spores actually reproducing was quite rare.

It did like building caverns. Delicately daubing sheets of moss across walls, laying down thickets of giant mushrooms, blending in delicate whorls of bioluminescence. It had unlocked many different fungi and modified them heavily, just for decoration, without ever really branching out into a proper specialization -- by which it meant, a system-approved spawning fork which provided greater practical use. It just liked glowing things.

Which was to say, it did like building caverns, but now it all seemed grotesque. Painting more artful, artificial landscapes, for adventurers to one day trample through... why bother? It had done that for floor after floor, elaborating on caves and caverns and dark fissures and striated canyons and subterranean lakes. Mimicking, in some sense, what a cavern network might have looked like here. If there had been one. Several miles outside its range, but still close enough to vaguely feel the shape of, there was an actual series of caves. Etched out, it thought, from erosion: some aquifer was pushed up by the weight of the mountain range above, leading to a series of springs and streams that ran intermittently all across the mountain slopes. One of those streams had found a weak patch of soft limestone and eroded through, forming a deep cenote that fed an underground river all the way through the mountain, and it was that cavern that it had idly mimicked over the years: forming out galleries and shelves as if they were eroded by the passage of water. Ignoring, of course, the constant downward slopes to the next floor, utterly unrealistic for any cavern carved out by the passage of water through. Through what? The dungeon had only ever had one entrance, and that had never been submerged.

Enough caverns, enough mimickry. It wanted to make something meaningful. Something real. But of course, it was much easier to flatly state that goal, without any other ideas, than to figure out what was meaningful. Its own adventurers? Its own gods? It was all cycles. It would like to make something that wasn't a mindless simulacra of something it had never known outside of system boxes informing it of the meaning of everything it was creating.

That was easier said than done. It spawned a level 1 goblin down on the barren floor 51. It did it slowly, watching mana spin into bone, tendons, ligaments, organs, muscle, and finally flesh. The resulting goblin stood there, looking around dull and incurious, and Goblin Cave released its grip on it, letting it act freely. There was no perceptible difference.

Its monsters did need to breathe. They could suffocate and drown, and previously it would have said, of course, that was because they were living things, but now it was concerned that was simply a balance consideration. The system status for mobs mentioned if they were aquatic or unbreathing, and those were specific tags with mechanical implications. Breathing might be a system-enforced mechanic, rather than... respiration. Like a living thing did. Or it might not. There wasn't really any way to test that, aside from sealing a breathing spawn somewhere airtight and seeing if it eventually suffocated from using air, and Goblin Cave did that, sealing the newly-spawned goblin in a perfect cube of rock. It didn't react. But, of course, there was no reason why a spawned goblin wouldn't breathe like a living thing without actually doing anything with it aside from converting live air to stagnant air.

The cube, though, gave it an idea. It had spent so much time carving out these false naturalistic landscapes, and there was something about the obviously-constructed sharp angles of the cube that sparked something. It shattered a nearby wall into a mess of variously-sized tetrahedrons, watching them tumble into a bizarre slope of geometric gravel, and then did it again with cubes, neatly slicing the wall apart in a space-filling grid, revealing layers of constructed dungeon granite mixed in with the real thing, imperceptible to anything that couldn't see the subtle variations in structure between dungeon-stuff and true rock. Octahedrons, rhombic dodecahedrons, a series of spiky stellations made out of pentagonal trapezohedrons, from 10-sided to 110-sided, at which point they just looked like two cones stuck together. It slowly permuted the stone: spawning new polyhedra in the various flavors of rock the system had unlocked: granite, olivine, limestone, and so on, and then used its own ability to tweak them: pushing a massive cube of pure quartz up from the ground, milky white and flawless, and then repeated the process with feldspar, forming a nearly-matching cube. By the end of it all, the barren cavern was awash with polyhedra in dozens of materials, and also the goblin in the cube had suffocated. If that meant anything. It shuttled its soul off to respawn in one of the rapidly-cycling upper floors.

The sheer artifice was satisfying, at least. It would be impossible to see the mess it had made and not think someone had done it, rather than believing it to be a natural process. It was done with faking natural processes.

Goblin Cave was tempted to simply stop respawning goblins on its upper floors. Congratulations, adventurers; you've finally destroyed the goblin menace! Now have the barren caves, devoid of life, which your actions have wrought. But...

It was afraid. Whatever the adventurers were doing, they were stable now, a known quantity. If it started acting differently, who knew what they would do? The obvious answer was: delve deeper. Kill and kill through its spawned monsters until they reached the end of its dungeon, and then shatter its core. Or take control of it, and force it to spawn nothing but level 1-5 goblins for the rest of its existence.

If it wanted to do something new, it would have to maintain its current levels, at least for the time being. In the mean time...

It carved a perfectly straight square passageway out from its 51st floor, and slowly condensed the material of the walls, feeding it mana until it burst to life as manastone.

Manastone A low-tier mana-conductive material, generally found in pockets near areas of high mana density. Raw mana fills the structure of the stone lattice, giving it vastly increased hardness and shear strength, as well as giving it its characteristic blue iridescence and faint glow.

Goblin Cave picked it because it resembled the blue crystal of its core: the most obviously artificial material possible. On a whim, it extended the corridor, forming a square chamber, and then dug off again at a right angle. It had an idea now: it dug out a replica of its first floor, all four linear rooms of it, but instead of the naturalistic caves and winding corridors above, it did it in sharp 90-degree angles, under the uniform, shadowless light of manastone. And to match the four rooms, it spawned in...

It had templates upon templates of spawns. All sorts of goblin varieties; a smaller but still vast list of beast templates ranging from mice to mammoths; a haphazard selection of other, non-specialized templates. But they were all simulacra. What this was was a dungeon mob: a thing that existed only to fight and die. Even the few elemental templates it could spawn -- wind shade, flame wisp, animated pebble -- were imitations.

Flame Wisp The lowest rank of fire elemental, a flame wisp takes the form of a hovering flame. Borne from unfocused mana in mana-rich regions, their color is usually pale and of varying hues.

What unfocused mana? Goblin Cave knew exactly what its mana was doing. This wasn't some creature bursting out of nothingness simply due to mana fluctuations; Goblin Cave was spawning it in.

Lacking any further ideas, it burned mana into nothingness, filling out the framework of a template spawn without having anything to put inside it. An empty, spawn-shaped box. The system didn't bother recognizing it, of course, but Goblin Cave was pleasantly surprised to see that the mana framework was at least self-stable: it withdrew its touch and the half-finished spawn remained, floating there as a visible web of mana threads. It added six more, near the cubbyhole warrens -- here, in the manastone replica of the cave, rendered as shallow doorways onto sheer walls -- where it spawned in the goblins out of view.

Then, for the [Goblin Chief], it made another hollow spawn framework at the end of the linear chain of rooms, and pumped in more mana, until it reached the amount required by a level 1 boss. There, though, something unexpected happened: the spawn template activated, condensing down and animating into a shape something like a shadowy humanoid figure, without any detail or substance.

New creature template unlocked: [Lesser Mana Puppet]! Lesser Mana Puppet A simple construct of pure, unaligned mana, forming a hollow animating figure without thought or will, capable of obeying simple commands. Critically weak to all magic damage.

Goblin Cave felt a burst of joy mingled with frustration: joy, because for the first time in its entire life, the creature description was wholly and truly accurate; and frustration, because... it had thought, in some sense, that it was being original. That it had had a new idea. But no, apparently it was still treading well-categorized ground. [Lesser Mana Puppet] fit in with the rest of its spawns: in its otherwise-patchy low-tier elemental construct category, filling in the 'elementally unaligned' slot in tier 0, next to the earth-aligned lesser stone golem. Its entire template codex could be reduced to this single one; arguably, in a sense everything it had ever spawned was simply a slight variation on the theme of [Lesser Mana Puppet].

Well, if it worked, it worked. Goblin Cave shuffled the hollow frameworks around, replacing them each with a [Lesser Mana Puppet], and then attempted the boss again: this time, it pumped in mana, stifling the activation of [Lesser Mana Puppet] in the same fashion as it stifled the spawn of a [Goblin] when it was trying to spawn a [Fierce Goblin], and kept going until it felt the system trigger again.

New creature template unlocked: [Common Mana Puppet]! Common Mana Puppet A construct of pure, unaligned mana, forming an animating figure without thought or will, capable of obeying simple commands. Weak to all magic damage.

That would do, for the 'boss'. A fractionally-improved version of the common dungeon enemy, like its [Goblin Chief] was to its first-floor [Goblin]s.

Looking at the tiny, idiot warren in the middle of the barren cave, Goblin Cave felt proud of its work for the first time in a long while. It was absurd. It thought of transposing the entire thing up to the actual 1st floor: Adventurers suddenly traversing its constructed hallways, goblins replaced with mechanically-identical mana constructs. The artifice of what they'd been doing all along peeled away to reveal the truth of the matter, so that they couldn't even imagine they were, what? Rooting out a goblin infestation?

It didn't do it, of course. It had meant it about needing to maintain its routine. But it was tempting.

More importantly, it liked it. It had been... fun.