Lu Yuan looked towards Caoyuan.

"You are responsible for teaching the two newcomers how to use guns, using the live ammunition left by the Raiders for target practice."

"Yes!"

"After they learn, pick a time, and everyone will go to the underground cave together to get some practical training."

"Understood!"

What Guo Li Cheng and Nan Guo de Xue received were the advanced automatic rifles confiscated from the Raiders.

Now, this automatic rifle has been officially named "Madman". After testing by Caoyuan, it was found that its overall performance is at least 20% better than the "Striker", which was produced in the 1980s.

Its complete blueprint has been entered into the 3D printer, and it will completely replace the "Striker" with overlapping positioning in the future, until better weapons are acquired.

"First, I'll teach everyone how to load, chamber, and switch the safety on and off, as well as how to select the firing mode. Then, we'll start practicing with the most basic prone shooting."

On the sand, Caoyuan said to the two newcomers who had put on their combat uniforms.

"Your targets are the wreckage of the all-terrain vehicles left by the Raiders earlier. Originally, ballistic computers were to be installed on the rifles. After the ballistic computer is connected to the tactical helmet, it will greatly reduce the difficulty of aiming."

"However, to get familiar with the firearms and develop a feel for shooting, we won't use it for now."

"Okay, Instructor!"

Guo Li Cheng clenched her fists.

Less than 5 minutes after going online, she had completely forgotten that this was a "game" and felt incredibly excited about using guns.

There was no way around it; the game's "graphics" and "sound effects" were too realistic, not to mention the tactile simulation.

Lu Yuan quietly observed for a while, then turned his head to look at the tall spaceplane.

With the danger removed, it was time to get it flying again.

The spaceplane's four jet engines are installed on the main wings and flaps, respectively. The nozzles can be angled downwards, providing stable vertical takeoff and landing capabilities.

To repair the engines, the entire jet engine needs to be disassembled first. After disassembling, the damaged parts inside need to be replaced, and then it needs to be reassembled as it was.

In other words, he also needed to build at least one electric hoist. Otherwise, with a single engine weighing over two tons, disassembly and installation would definitely be impossible with just manpower.

Considering that the ground beneath was soft sand, a stable metal base also had to be built for this hoist in advance.

In addition, repairing the fuel lines requires maintenance personnel to first climb onto the back of the aircraft, remove a section of the skin, and then perform welding.

A sufficiently long folding ladder was also indispensable.

Lu Yuan thought about it. The design and construction of these pieces of equipment shouldn't need to bother Jubian. After initially mastering the use of the 3D printer, he could handle it himself, and the raw materials would only require the scrap metal left by the Raiders.

The main thing was still to gather the rare metals as quickly as possible.

Both newcomers learned very quickly, especially Guo Li Cheng. Her shooting aptitude was only slightly inferior to her cousin, Ye Xing.

The subsequent team dungeon runs were also very smooth. The firepower of the 5-person team could basically walk sideways in the underground cave dungeon. Although Nan Guo de Xue could only fire in bursts from a standing position due to insufficient strength, she didn't show any panic during combat.

Presumably, she had already built up her courage from playing horror games before.

Back inside the spaceplane, Lu Yuan designed the hoist while having the 3D printer continue producing solar panels and ammunition.

Another day passed.

Thanks to the players' unremitting efforts, the collection progress of vanadium and nickel reached 93% and 289% respectively.

A total of over 35 kilometers have been explored within the underground cave. Passages leading to deeper areas have been found in all directions, and it seems the entire Desert's underground is connected.

Moreover, the deeper into the cave they went, the more likely they were to encounter Mechanical Desert Spiders.

This phenomenon attracted Lu Yuan's attention.

On one hand, this was beneficial for farming materials, but on the other hand, it also made him feel a sense of unease.

"Shen Quan," Lu Yuan called the native boy over, "there's something I want to ask you."

"Yes, please ask."

"Regarding the mechanical creatures underground, does your Red Iron Town know much about them?"

"We're quite familiar with them. We all call those mechanical beasts 'Mech Guardians'. We often encounter them while mining. Legend has it they were left behind by the planet's early colonists, about eight or nine hundred years ago."

Shen Quan said.

"But we don't have firepower as strong as yours, so we usually try to avoid them. Also..."

"Also what? Just say it, it's okay."

Shen Quan sighed, "The older generation is very superstitious. They believe that provoking the Mech Guardians will bring about very bad things. They would rather reduce the mine's output than venture deep into their territory."

"What specifically are these bad things?"

Shen Quan: "According to the old folks, a long time ago, a mining town decided to go to war with the Mech Guardians. They bought a lot of weapons from Oasis City and the fighting went smoothly at first, but from a certain day onwards, the situation took a sharp turn for the worse."

"And then?"

"Then one day, they sent out a distress signal to the surrounding villages and towns. When the people from the surrounding areas arrived, the town, which originally had over 200 households, was completely empty. There were bloodstains on the ground left by humans being dragged, and the bloodstains all converged towards the entrance of the mine shaft. No one dared to go deep underground to search for the missing people..."

After listening to Shen Quan's narration, Lu Yuan fell into deep thought.

It was clear that for territorial infringements of general intensity, the Mechanical Desert Spiders would only carry out expulsion.

However, when the invasion behavior reached a certain intensity, their combat power would greatly increase.

This could only be due to temporary body reinforcement modifications. Otherwise, the killing efficiency of those four small steel claws was really very limited...

These reinforcements consume extra energy and are usually a burden. Therefore, they are only installed when "war" arrives.

At least on a logical level, this makes sense.

So, to install these modified parts, there must be a place deep underground similar to a workshop, and it's highly likely that there is a mother host with a higher level of artificial intelligence responsible for controlling the collective behavior of all nearby Mechanical Desert Spiders.

"In other words, you have never found the nest of the Mech Guardians?" Lu Yuan finally asked.

"No." Shen Quan shook his head. "We're not even sure if they have a so-called nest. People from other villages and towns, including Oasis City, probably don't know either."

"Knowledge and wealth might be hidden in the nest..." Lu Yuan murmured to himself.

Gains are always accompanied by risks. For Lu Yuan, recovering the human technology of the golden age was very important. A mere mechanical race could not become a stumbling block.

Moreover, it currently seems that the players' firepower has not yet triggered the Mechanical Desert Spiders' collective defense mechanism. In the future, as long as the size of the dungeon-clearing teams is limited, for example, not exceeding 4 or 5 people, this relatively safe state should be maintained.