Catty Catty Catty

As disaster was about to strike, a group of survivors transmigrated into a desolated world and were challenged to a game of survival. From terrifying acid rains, to endless natural disasters, the heavens burn while the earth scorches, radiation is rampant, and nobody is spared from the dangers of this hellscape. The only way one survives is by building a shelter and slowly upgrading it in hopes of surviving another day. 
Luckily, Su Mo awoke a Doomsday Survival System that allowed him to infinitely level up and upgrade his shelter! The main shelter wooden door can be upgraded into a metal door, which in turn upgrades into a composite gate; the wooden spears can be upgraded into bronze spears, which eventually upgrade all the way into electromagnetic spears... While everyone struggled to survive, Su Mo was fully loaded, and well equipped to dominate the post-apocalyptic world. 
"While some of us are lighting oil lamps, he's been using refrigerators!" 
"The walls in his shelter alone are tens of meters thick, it's the safest place on this planet."
"Before I die, I wish to spend one day in his shelter..."

EndlessFantasy Translation 

My Post-Apocalyptic Shelter Levels Up Infinitely!

LambSheepMutton

Liu Cheng immediately reported the newly discovered fact after calling the excited Li Hu, who observed them from a distance.

Through the gap they created was a combination lock that looked overwhelmingly complicated.

From left to right, there were twelve rows with incomprehensible symbols on them.

Just above the symbol sequence was a copper lever that could be triggered.

The twelve rows with symbols had to be in their appropriate position, and the lever had to be pressed down, causing the mechanism inside to unlock itself.

Upon successfully unlocking the door, the lock plate placed inside would also begin functioning to pull or push open the door, making room for entry or exit.

The method was very old-fashioned but highly reliable.

There was no need to rely on any facilities that required energy, nor would there be any reliability issues that would occur.

First Time Opening the Door, the Seven Alphabets! Part 3