"What is this…?" Xu Xin picked up the gray potion.
[Special Tree House Root Enhancement Potion (Purple): When poured under the tree house, it can promote the development of the tree house roots, expanding the protection range of the tree house by three kilometers per dose.]
A purple-grade potion! And one that expands the tree house's protection range!
Xu Xin's current tree house protection range was three kilometers in radius. After using this potion, it would expand to six kilometers! This wasn't just doubling the size – with the protection radius doubled, the area would increase fourfold!
In other words, after using this potion on his tree house, Xu Xin's area for exploration and activity would become four times larger than before! And within this expanded range, there might be another resource area.
It was indeed a good item, truly befitting a golden chest.
Xu Xin then picked up the thin card.
[Metal Products Automatic Unlock Contract (Purple): Can unlock all metal product recipes. After using this contract, for all metal-related crafting recipes, they will be automatically unlocked as long as you have obtained all types of raw materials.]
Following the tree house modification contract, he had obtained another contract, this time for metal product recipes!
With this contract, Xu Xin would finally be able to craft more than just stone tools!
[Congratulations, you have opened gold, silver, and copper chests, becoming the first among this batch of survivors to find and open all three types of chests. The reward will be issued after the conclusion of this jungle exploration activity.]
[Please continue to strive, survivors. Strengthen yourselves and work hard to survive in this world.]
The mysterious voice sounded again.
He was the first person to obtain all the chests.
The activity hadn't ended yet, and it was unknown whether others would find the golden chest.
Honestly, if it weren't for Coco saying there was a golden chest below and insisting on pulling him down, with his cautious nature, he would never have crawled into this hole and dug out the underground passage.
The conditions for obtaining this golden chest were indeed extremely harsh.
Xu Xin shook his head, not dwelling on these thoughts, and chose to use the contract in his hand.
Just like last time, the card representing the contract shattered in his hand and merged into Xu Xin's body. Xu Xin felt a surge of power flowing through his entire body.
This time, he not only felt stronger, but even felt his mind becoming clearer. Everything he had just experienced was quickly sorted through in his mind.
First, that giant man-eating flower must be the monster guarding the entrance to this underground world.
The iron room underground, along with the person inside, had been buried underground for many years, but the unbearably foul red mist in the room came from an unknown source.
The person in the room was not from this world, yet brought tools and food from Xu Xin's original world, indicating that their method of arriving in this world was different from Xu Xin and the other survivors. But exactly how they came, Xu Xin couldn't figure out now.
The golden chest for this mission and the secret of the underground space were bound together. The golden chest must have been deliberately placed in this location. Anyone who discovered the golden chest would definitely see the secret of this underground world before finding the chest.
And those who couldn't find the location of the golden chest naturally wouldn't discover this secret.
Who exactly was that mysterious voice? And for what purpose were they brought to this world? Could it be to have them grow stronger and then confront those monsters deep underground?
How were those monsters created? The size difference between them and the surface creatures was too great.
He recalled the giant anaconda in the lake and the giant crocodile in the stream. These two extraordinarily large creatures must have come from underground, and what the lake connected to below was likely the underground world a thousand meters deep.
Then there was this potion from the golden chest.
Xu Xin examined the gray potion in his hand,
The whole bottle contained about 300 milliliters, with a weight similar to a bottled drink. The potion's effect was to promote the development of the tree house roots, expanding the tree house's protection range. Did this mean that what protected Xu Xin and the other survivors from underground creatures were the roots of the tree house?
An image appeared in Xu Xin's mind.
During the two hours when the tree house was growing, as the above-ground part of the tree house grew, its roots were also branching out underground, extending in all directions up to three kilometers away.
The tree house roots spread intricately underground, blocking monsters trying to emerge from below. Once a monster appeared, it would be absorbed by the tree house roots, quickly turning into a dry and brittle specimen.
So when the tree house roots developed longer, the protection range of the tree house would correspondingly increase.
Xu Xin felt this explanation made sense.
This also explained why the mysterious voice repeatedly emphasized that they must never abandon the small tree house – because the tree house was the most powerful weapon and greatest safeguard against the underground monsters.
Having understood all this, Xu Xin's mood eased a little. According to what the mysterious voice had said before, the underground monsters wouldn't attack them in the near future. They only needed to focus on dealing with the beasts on the surface.
The tree house would protect them well.
Xu Xin put the golden chest into his backpack. Although the golden chest was made of gold and very heavy, Xu Xin's strength had been enhanced several times and he was no longer his former self. Combined with the backpack that reduced weight by 20%, carrying this chest on his back posed no problem.
He was actually looking forward to what might happen after collecting all three chests and completing that pattern.
Before leaving, he decided to take one last look at the underground world, as he probably wouldn't return here for a long time after this.
Coco, however, didn't approach the cliff edge like him, but stayed behind, crouching and keeping a fearful distance from the precipice.
It was still the same scene of chaotic monsters.
Giant creatures covered in seaweed, man-eating flowers several times larger than those on the surface, blood-red vines everywhere, firefly-like creatures the size of small cars, and various other gigantic flora and fauna that could never exist on land.
These were the things he would have to face in the future.
He must quickly improve himself and gain the ability to confront these creatures!
Xu Xin looked ahead, his gaze suddenly focusing.
At the top of the entire underground world, he saw many downward protrusions.
Xu Xin's current position was equivalent to a light on a room's ceiling, and those protrusions were like other lights.
"These protrusions should be the tree houses of other survivors, or rather, the roots of their tree houses," Xu Xin pondered.
According to his deduction, the interiors of these protrusions should be the intricate roots of the tree houses, used to protect the survivors from these underground creatures.
"Although I don't know who brought us here, they must be playing a grand chess game."
Xu Xin took one last look at the underground world before turning back to the iron room.
The skeleton was still scattered on the ground. Xu Xin grabbed Coco, who wanted to go play with the skull, and placed it on his shoulder.
"Yin!" Coco let out a dissatisfied cry, but still obediently lay on his shoulder.
The next task seemed simple yet not so simple.
Climb up!
Looking at the deep passage, Xu Xin felt his legs trembling.
Just climbing down had made his arms terribly sore, and now he had to climb up!
He was even carrying a golden chest on his back!
It would kill him with exhaustion!
Xu Xin looked at the little fellow on his shoulder: "Can you climb by yourself?"
"Yin yin yin!" Coco shook its head vigorously.
"You lazy thing!"
"Yin!" Coco wanted to argue – the distance between each step was almost as long as its body, how could it climb!
Sighing, Xu Xin decided to eat something before climbing. After all, he had vomited everything he ate last night up there, and although the recent contract had restored some of his strength, he had been down here for so long that it was probably daylight above and time for a meal.
Just as he took out an apple to bite into, a hissing sound of air release suddenly came from beside him.
"What's that sound?"
Xu Xin turned back vigilantly.
To his horror, the half-open iron door suddenly closed automatically with a loud bang. Then, a familiar red gas began to spurt out from the cracks between the walls and floor of the iron room, gradually spreading.
"Oh crap!!!"