Time Reaper: Rise Of The Blood Monarch - Chapter 1: Prologue.

In a world where magic rules and human nations fight to survive, a 14-year-old stowaway finds himself thrust onto the frontlines of war. With no allegiance but to his own cold logic, Lugh is forced to navigate battlefields of steel, sorcery, and shadows. What begins as an escape soon becomes something far greater—whether he wills it or not.Gunmage – When spell and steel collide, a new kind of warrior is born.

After breaking up with his girlfriend, he accidentally acquired a genius system and rose from there against the heavens, becoming invincible..

- Description from Novelupdates

Riding out the apocalypse on a tropical island isn't exactly a vacation. When mana arrives on Earth, Coop finds himself isolated in paradise with only one real option to survive. He needs to claim a civilization shard and level up. Coop maximizes his chances by carefully selecting a class and committing to progression. He’ll need to grind thousands of monsters to compete on the system's leaderboards while upgrading his settlement to represent the factionless.