Harem of the Dora Prince - Volume 1, Prologue

It is a parallel world that is full of Star Power. Star Maps, Star Techniques, Star Pets, and the Awakened are rampant. Jiang Xiao, whose soul travelled to this world, has a special internal Star Map within his body and goes on to become a Medical Awakened.

Roy’s life was nothing special. The only thing commendable was the last few moments when he saved a mother and her child from a drunk driver.
…
It’s really an egg! Damn it, what kind of monster have I become? Did I fall into Hell instead of making it to Heaven??
Join Roy as he ventures through various worlds with the Custom Made Demon King System—a system that allows Roy to draw anything he can imagine and create it through exchanging souls!

Protagonist travels between different anime worlds to right wrongs and uncover his reason for being along the way.

- Description from Novelupdates

The labyrinth that swallowed humanity. Four choices were given to them.

Easy Mode, where anyone can survive. Normal Mode, where only those who fight survive. Hard Mode, where only 1% can survive. And the Solo Mode, where only one person survived.

The strongest returnee of humanity, Kang Taesan, was an Easy Mode player.

He heard countless times,

“What if you had chosen the Hard Mode, or even the Normal Mode?”

Regretting his cowardly choice while dying amidst destruction, he gets another chance to choose.

“This time, I won’t make the wrong choice.”

The strongest Easy Mode player has returned.