Doomsday: I, the Extraordinary Mechanic!

It was the year 2055. The Zombie Virus had erupted and doomsday was near. The world order had collapsed!
Humans used nuclear weapons once again to eliminate zombies all around the world. They cleansed the population with the extreme means of destroying cities.
However, what they did not expect was that zombies had unimaginable vitality. Not only did the nuclear weapons not eliminate the zombies, but they created an even greater disaster for humanity. Nuclear radiation ravaged the world. The water was no longer clean. The ground became dead zones. Even the houses they lived in were no longer stable.
The zombies even mutated to become fiercer and more terrifying! Humans struggled to survive under the arduous living conditions and manic zombies.
Johnson awakened the Legendary Mechanic System and was living extremely comfortably in the post-apocalyptic world.
When the others were still fighting each other for a piece of bread or bottle of water, Johnson already had a purification machine which gave him ample food and could even have a bubble bath with clean water.
While the rest of the population were still hiding in ruins and shivering in fear, Johnson had already modified an abandoned factory into a sturdy refugee base. Unmanned blasters, giant destructive cannons, superpowered scout robots, laser towers... There was only one rule for entering Johnson's refugee base... You have to be a woman!