Tensei Shitara Slime Datta Ken (WN) - Chapter 264

Mason was a mercenary, until the day he died on a mission after being betrayed by his unit.

A supreme expert in the Immortal World had died, and a strand of his soul returned to its original body on Earth. Tang Xiu discovered with amazement that ten thousand years passed in the Immortal World, yet only a single year passed on Earth.

Ruthlessly betrayed by his lover and trusted friends, Tang Xiu found that his soul went back to his previous body on Earth, and, despite he spent 10,000 years in the Immortal World, just a year has passed on Earth and many things have changed. Having an unsurpassed knowledge, Tang Xiu will protect his loved ones and go back to the Immortal World to take his revenge.

- Description from Novelupdates

Even though Gu Yunxi was created from the accumulation of the resentment of souls, there was not a bit of ruthlessness nor cruelty in his nature, only a desire to cultivate. Just as he achieved his human form, he was sent to reincarnate. Under the control of Heaven, he experienced life after life of suffering, dying a terrible death every single time. After thousands of reincarnations, thousands of terrible deaths, he finally accumulated enough power to escape from the Laws of Heaven. He swore to get revenge on this blind Heaven’s Law that’s unable to differentiate good from evil.

So what if it’s the Heavens? He will stir up the rights and wrong, the good and evil!

You want me to accept this life and die, but I just won’t! I want to live, to rebel against the heavens, to reverse this joke of a destiny!

- Description from Novelupdates

If I were to fall into a game, I wish I would fall when I was young.