System: My Doomsday Train - Chapter 9: 14 Buildable Vehicle Accessories.

In 2040, The Earth was bathed in powerful radiation when a star went supernova, this radiation granted 50% of humans superhuman abilities but also created a nightmare for them as animals, insects, and carnivorous plants were mutated and became overpowered with intelligence, human started teetering on the brink of survival, a boy with no powers and no father, with a mother in a coma, seems destined for obscurity, but one night changed his life, with a new found hope to cure his mum from the everlasting sleep—Gene Elixir— he went on on a journey that would reshape his destiny...~Voracious Sovereign... Gene Devourer...Pray you won't be devoured by this power you wield which hunger is insatiable~~You call yourself an opportunist... But... you aren't free. A hungry man is not a free man...~

Found a suitable body named Bai Xiao. Reincarnating into the World of Elementalists.

“Mission: Overpopulation of carnivorous fish in the lagoon.

Please kill 666 carnivorous fish in order to prevent the destruction of the lagoon’s ecosystem.

Reward: 20 Balance Points.”

“Mission: Forest fire.

Extinguish the fire.

Reward: 200 Balance Points.”

- Description from Novelupdates

In an alternate world, a demon disrupts dynasties, harvests souls, and refines a banner of ten thousand souls.Under the heavenly tribulation, his body and soul are destroyed, but the Ten Thousand Souls Banner protects his undying spirit. Unable to possess a body, he's countered instead.A laid-back young man in society, wielding the Ten Thousand Souls Banner, roams the human world.With the Ten Thousand Souls Banner in hand, I refine a Golden Core with good deeds.A slice-of-life story with no ambition for conquest, helping the departed fulfill their wishes, gaining merit to repair the Ten Thousand Souls Banner, and enjoying a laid-back life.

Jiang Chen had unexpectedly found himself thrust into a world of cultivation, stepping into the role of a core disciple within a famed sect. Fated to be the villain, his future loomed with calamity. He had plotted against the protagonist, crippling his dantian and leaving him a disgraced outcast teetering on the edge of expulsion. Were it not for an unexpected twist, Jiang Chen’s part might have ended as a mere footnote in the protagonist’s glorious tale. Fully aware of his precarious position, Jiang Chen’s lips curled into a sly grin. Alone, he mused: ’Is the protagonist powerful? Without a doubt.’ ’But will I tremble in fear? Absolutely not.’ ’Why? Because I have the Immortal Great Villain System!’ ’Wait... there’s more than one protagonist?’ ’Well, isn’t that just perfect?’ With a determined glint in his eyes, Jiang Chen declared to himself, ’As the ultimate Great Villain, I will defy the will of Heaven and seize my place at the summit!’