Run Away, This Civilization Is Cheating! - Chapter 334 - 298: The Era Belonging to Human Civilization!_2

He Lang died by his own hands for the sake of his imperial younger brother’s ambition, whom he loved. He was offered to be reborn in exchange for giving up his past romantic feelings. Reborn without the burden of his romantic feelings, he brings with him a manual to new worlds. He wholeheartedly followed the instructions of the manual to complete the tasks, not knowing that the originally slag gong was blackening…
He pleaded to his affectionate Emperor brother to release him, he pleaded to the paranoid prisoner next door, but until the end he remained baffled.
In the end, he discovered that the full name of the manual was – “Slag Shou Cultivating Manual”
Σ (っ ° ° °;) っ!

- Description from Novelupdates

Felix's life on Earth had become a series of dead-end jobs, ruined relationships, and rotating apartments smaller than most postage stamps. By all accounts, even his own, he was a coward. Too afraid to move forward, to take risks. Yet when given the chance to choose between risking his life or walking away from a deadly encounter, he didn't hesitate.Moments before his untimely demise, Felix was snatched from earth and thrust into a magical world known only as ‘The Continent’. Empowered by the ‘System,' he learns that he can strengthen himself through combat and dedication. To survive he'll have to push himself beyond his limits, or else fall to the monsters all around him.Levels, stats, and magic. Death is the start of a terrible fate, but if he lives…who knows what he will become.

I got transmigrated into a game I’ve never seen before.

I thought it was a top-notch RPG and spent 30 years on it.

I retired as a war hero and planned to spend my remaining time leisurely.

But it turns out, it was an academy story?