Robert woke up to find himself transmigrated into a world that had been invaded by demons. The demonic energy was consuming the world, which would end up leading to the world being destroyed. 
During the time that the invasion occurred, the world granted all the beings within a way of getting stronger. They could gain a technique that was solely theirs at the age of 20, which would allow them to be able to absorb the natural energy in the air in order to grow stronger. 
Due to the invasion of the demons, the world released a lot of its energy, leading to different types of resources emerging. These resources could also be used in advancing the power level of a person by absorbing the energy contained within them. 
But more than that, it seemed that this world was previously so powerful in the ancient times. By exploring the world after getting more powerful, with ancient ruins being revealed one after the other, people realized that they could find techniques, skills and many more things within those ruins. 
But it was not that easy to explore those ruins, considering that the demons, understanding that this was a method that the humans could use to get stronger, occupied any area that a ruin appeared. 
The more powerful and ancient a ruin was, the greater the number and more powerful the demons occupying that area were.
 But that was not all. The demons would occasionally attack the strongholds that were remaining, trying to make sure that they could wipe out the entire human race as soon as possible. This was just a measure that they were taking in order to make sure that the humans did not develop to the level that they could resist them.
The only saving grace was that the world’s will, understanding that if it allowed the demons to completely occupy the world, it would crumble, used a method to protect itself. It created a barrier that could only allow low level demons to invade this world. As for the high level demons, they could not penetrate the barrier, at least for the time being. 
As the demons outside this world continuously attacked this barrier, while those inside continuously killed humans, the barrier was weakening, and higher level demons could progressively enter into the world. 
After understanding all this, Bob wished that he could go back to Earth. He liked the life that he had been living before, and was not willing to get himself engaged in something like this. 
But just as he thought about that, a translucent holographic screen appeared in front of him.
[System binding…. System binding completed. System activating…. System activated.]
[Welcome to the Infinite Skill Upgrade System.]
[With the assistance of the system, all the skills can be upgraded to the highest level possible. There is no limit.]
But was that all? It was not! The system was actually glitched! Maybe he was supposed to work, so that he could get the skill points that he could use in order to upgrade the skills. 
But for some reason, his current number of skill points was actually….
Current skill points: ∞
What would happen next? Would he be capable of using this glitched system to resist and survive in this demon infested world? Would he be able to go back to Earth?

Power levels (Each has sublevels from 1-9)


Weapon Categorization (Based on rarity)


Auxiliary Chapter for Arc 1