The blue screen popped up as soon as they finished with their last boss.

Expansion of your sub-dimension from completing your tenth floor will now commence. Due to finishing the first ten floors of your dungeon, your sub-dimension will gain an additional ten-metre expansion in width and height.

The maximum number of monster species within your dungeon has now increased by three until the completion of your fifteenth floor. This does not include monster species obtained from outside your dungeon.

You have now gained the ability to set different dark or light areas within specific rooms or floors.

You have now gained the ability to have all rooms be indestructible. Outside forces or mana will not affect rooms, floors, and ceilings. Only a dungeon core’s mana can change them.

You have now gained the ability to create linked theme floors. Interlinked theme floors are floors that appear to be one very large floor. These floors tend to be built together and follow a similar theme.

They read the five blue screens and felt their skin tighten as their sub-dimension expanded and their floors and tunnels slightly moved around.

But that was not the only change.

They grew.

It was like their body aged just a tiny bit.

Their body increased in height, and in their arms, legs, hands, and feet grew just a tiny bit, but enough for the child to notice. And their hair grew just a centimetre longer, down to the tips of their ears.

It was weird. As the child observed themselves and looked over the changes. Stretching out and feeling the lengthened muscles under their skin, the child took a couple minutes before they attempted to walk again.

Taking that first step, the child stumbled, muscles still weak and new. Here we go again, though the child, grumbling as they recalled their first-ever attempt at walking. But as the child moved around more, they got the hang of it again.

Once they mastered their new body, the child started thinking about their next floor.

Or rather floors.

If what the blue screen is telling them is valid, they can start linking floors as long as they have the same theme.

But they have to settle on something they can continue for at least two floors, as the past ten floors haven’t precisely followed a theme.

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Hours went by as they started thinking up and narrowing down ideas.

At first, they wanted to do something like the greenhouse, well, more of an overgrown area with a ton of plants that were not on structures. But they scratched that idea because they didn’t have enough non-aquatic animals to do this for more than one floor.

Their next idea was to take all of the pieces of debris and wood from destroyed ships they had been collecting and make a kind of storm floor. That is, if they can figure out how to use the lightning mana to create lightning strikes and water mana string to create rain. They liked this idea, but they didn’t want to do that just yet. Maybe later, but not now, they put the idea back in their mind and continued.

Their next potential idea was to do things like rock pools or sand bars with low water depth. The child was wishy-washy about this idea. While they thought it had potential as a single floor, the child didn’t know if they could do a themed linked floor with this idea.

The other idea they had took them back to their origin. Underwater ice caves. These caves will be completely submerged, and they took an idea from the brinicle krill boss monster. To drastically decrease the temperature the further you get, adjust all plants, creatures, and monsters to suit this environment.

After thinking about this, they decided to go with the underwater ice caves. And it was not just for the physical and environmental appeal; it was also practical. Having a set of floors completely or almost entirely underwater will limit and hinder any land-dwelling invaders or adventurers.

So, they got to work.

Now, they’ve imagined this floor becoming a natural cave system.

As they started digging out the rooms, the child didn’t even try to smooth out the walls. Each scoop they made as they cleared out the ice made indents within the walls.

And with the near indestructibility of their walls, the child didn’t even need to create pressurized ice walls anymore. So all that extra ice went into making these long pressurized ice pillars reaching up and down. These stalactites and stalagmites practically littered the room so much that the child realized it was too much.

So they cut some of the pieces of ice that ended in points, not cleanly, but more like they were naturally damaged and cut. Giving them a rough and natural look and a large amount of debris on the ground.

With the physical environment of the eleventh floor finished, they took a step back and observed every aspect of it.

The only thing the child had to compare their floor with a natural cave system was from an explored iceberg, which was only a very small series of tunnels and caverns.

But what they managed to create was similar in some aspects. The rooms were not conformed into one shape. They had slopes, blind spots in turns, and many cracks within the walls, leading to tiny spaces for tinier creatures. And ranged from ten metres to 20 metres wide and two metres tall.

The tunnels were a wide range of what looked like small rooms with small stalactites and stalagmites to areas where any human-sized invaders would have to squeeze through.

With the floor to their satisfaction, the child grabbed a water mana string from one of the floors and tried something new.

From floors one to ten, they have been opening tunnels to allow water to fill their floors. Which is both time-consuming and wasteful, as it tends to lower the water level on the previous floor, making the child go back and fix it.

But this time, they tried something new.

Grabbing the water mana string, the child pumped some of their own mana into it, hoping to see some results. And they did.

As the water mana slowly circulated through the floor, it started dripping, like the thread was raining.

Grabbing even more water mana threads out of circulation from other floors, the child flooded the rooms and tunnels with the threads. And all of them started raining and producing water.

By the time the threads filled the rooms about just below half their room’s height, the child had stopped them.

The water coming from the mana strings had a minimal amount of salt in it. Around one percent of it. It was essentially fresh water, and they knew that unless they wanted to forcibly adapt all of their oceanic creatures, who live in saltwater, they would have to add just enough saltwater that their creatures and plants can live in it.

Opening a direct tunnel into the fifth floor, and watched as the saltwater mixed with the freshwater. As the water from the fifth spreads into the floor, the water becomes saltier and saltier.

Well, that solves that problem. Smiled the child as the slowly more pronounced problem of bringing water to their further rooms solved, as they sent the water mana strings into the fifth floor to bring the water level back to what it already was.

But they kept back two water mana strings.

One to circulate throughout the room. And the other, they had plans for.