Global Cataclysm: Get level 3 civilization at the start

What will it be...

[This zombie wave attack is over! 】

[Congratulations to everyone for successfully resisting the attack of the corpse tide! 】

Noah's voice resounded throughout the star underground shelter.

Suddenly, everyone's faces were relieved.

The gates of the heavy metal protective barriers protect the people in the core area.

At this time, none of them knew.

Just around them, separated by seven or eight protective doors.

At this moment, there is still an army of zombies constantly attacking.

They thought the battle was completely over.

Started to cheer up.

Only Li Chen, Xu Ruoxi, Dang Zhongcheng and others are at the bottom of the underground.

Only at this time can I feel that the threat has not yet gone away.

"Commander, the zombies outside don't seem to have retreated."

"If they continue to attack, they will attack our underground command center!"

Xu Ruoxi reminded nervously.

"Just let me take people out to destroy them!"

Dang Zhongcheng raised the weapon in his hand, his tone full of determination.

"No need."

"They're going to die soon."

Li Chen waved his hand.

At this time, he has already received the reward from Noah.

10 billion evolutionary energy, 50 third-order energy crystal nuclei.

In addition, there are 18 fourth-order energy crystal nuclei and 5 fifth-order energy crystal nuclei.

But what makes Li Chen most happy is the number of 15000 sixth-order energy crystal nuclei!

These are all rewards given to him by Noah.

And add the energy crystal nuclei obtained by himself and various troops.

These things are going to double!

[Congratulations to the host for completing the challenge, the upgrade and enhancement functions of the star shelter have been activated for you. 】

[In order to save your precious time as the host, Noah has designed a variety of new underground shelters for you in advance for you to choose. 】

[You can also design your own host and upgrade the current star shelter! 】

[When the star shelter is upgraded, the enhancement function will be activated, and you can choose the specific enhancement content of the star shelter at that time. 】

[The super gift package issued for you has been placed in the system backpack, and the host can check and use it at any time. 】

At the same time as Noah's voice sounded, an illusory selection interface popped up in front of Li Chen's eyes.

On it are the upgrade previews of the star shelters, as well as related design drawings.

On the preview picture, in addition to showing in detail the various related attributes after the upgrade of the star shelter.

There is also the number of energy crystal nuclei that need to be consumed for the corresponding upgrade.

Li Chen was a little frightened just by looking at the upgrade price.

“升级预览图一，升级所需要的能量晶核：三阶能量晶核60万、四阶能量晶核30万、五阶能量晶核4万、六阶能量晶核1万2000！”

"I'll go... the price is too expensive!"

Li Chen looked at several other previews of the upgrade.

Fortunately, he found that although the upgrade structure and effect of the star shelter are different.

However, the number of energy crystal nuclei required for upgrading is the same.

"Commander? What are you talking about?"

Chapter 312 upgrade complete

At this moment, Xu Ruoxi, Dang Zhongcheng and the others all looked at Li Chen in bewilderment.

They heard Li Chen talking to himself.

Everyone has a puzzled look on their faces.

At the same time, I was a little nervous.

Only at this moment, the army of zombies outside is still attacking.

Constantly attack the fourth layer of defense barriers.

If you don't stop them, let them break through this fourth barrier.

Then they will directly break into the underground command center.

The underground command center is equivalent to the brain part of the star shelter.

If it is attacked here, the consequences will be disastrous.

Hearing the words of his subordinates at this time, Li Chen also came back to his senses.

Looking up at the crowd, he himself was slightly puzzled.

But immediately Li Chen thought of something.

It seems that only he can see the illusory selection interface in front of him.

Including Dang Zhongcheng and Xu Ruoxi, they couldn't see it.

This may be Noah's self-protection function.

After all, not everyone has Li Chen's authority.

If he wanted to operate the entire star refuge, of course Li Chen had to come in person.

"It's nothing."

"Wait for me a moment, I'm discussing something with Noah."

Li Chen nodded, and then communicated with Noah in his mind.

"Noah, think of a way to explain it to everyone."

"I'm afraid they won't be able to accept such a sudden upgrade of the star shelter."

"It's too magical for them after all."

Li Chen ordered.

[Host please rest assured, just leave this matter to me to explain. 】

[Please make your upgrade choice as soon as possible, the fourth barrier of protection can only persist for another 9 minutes at most. 】

After Noah reminded, he began to broadcast through the internal broadcast of the star shelter.

Start to explain to all the residents and fighters.

Li Chen didn't listen carefully to how it was explained.

At this moment, all attention is placed on the selection interface in front of him.

"Because resources are limited, each design approach addresses different trade-offs."

In the selection interface in front of you, there are a total of about twenty upgrade options.

And he quickly figured out the difference between these design drawings.

"For example, the first design drawing focuses on protecting the command center of the star shelter."

"So on the preview picture, you can clearly see that the command center of the star shelter has been fully reinforced after the upgrade."

"The position and functional attributes of each floor remain the same, but all the protective barriers in the bottom few layers of shelters have been reinforced, and the thickness of the original 1.5-meter mixed heavy metal barrier has been increased to 4.5 meters."

"The defense has been strengthened by about three times."

Li Chen thought quickly, and then set his sights on the second upgrade preview.

This upgrade preview focuses on strengthening the weapon production base, military training base, scientific research area, and the area where the core processor is located.

At the same time, take into account the strengthening of the underground command center.

But the same, because the energy and resources consumed by the overall upgrade are limited.

Therefore, the reinforcement of the above key areas is an average reinforcement.

The thickness of the protective barriers in each area has increased from the original 1.5 meters to about 3.0 meters.

As for the thickness of other regional protective barriers, it remains unchanged.

Li Chen is not particularly satisfied with these trade-off designs.

He tossed and turned, and finally his eyes fell on the seventh design drawing.

"This one looks pretty good."

This is a design drawing that fully considers the star shelter.

No area was abandoned, and no area was focused on strengthening.

It evenly distributes all upgrade resources to the entire star shelter.

Not only are newer composite heavy metal materials with higher defense strength used.

At the same time, the thickness of the composite heavy metal materials has also increased from 1.5 meters to 2.5 meters.

Another piece of good news is that after the upgrade of the star shelter.

All protective doors, as well as the internal single-layer protective barriers.

All crafted from a unique composite supermetal.

The defense will be much stronger than the original ordinary composite heavy metal.

"That's it!"

Li Chen looked at the time.

It's just such a short time for me to make a choice.

Another 3 minutes passed.

The zombies that broke in from the ground outside are still attacking.

The fourth layer of protective barriers is already crumbling.

Can only hold on for 6 minutes at most.

[The host confirms the choice of design blueprint 7, and upgrade your star shelter according to this choice? 】

[Once the upgrade operation is selected, it cannot be changed. It is estimated that the entire upgrade process will take about 30 seconds! 】

Noah's reminder sounded in his mind.

Li Chen thought for a while and nodded immediately.

"No problem! Let's upgrade according to the style of this design drawing!!"

He rubbed his hands.

After the star shelter is upgraded, other strengthening operations can be performed on it.

And just now Noah made it clear.

This strengthening operation can be DIY by yourself.

The degree of freedom is very high.