Tree of Aeons - Treeckets, Please

As a precocious child, Lycoris suffers from a strange sense of deja vu. On the day her father told her about her fiancé, she realizes that her fiancé was a character from an otome game she once played in a previous life.

Lingyun, a fierce and savage cultivation genius takes over a dead teenager’s body. Coincidentally, they are both named Lingyun. Set in a alternate version of the 21st century, teenager Lingyun has been killed by someone with a grudge.

- Description from Novelupdates

Due to the increasing cases of suicide in the country, the government created a simulator system that was linked with human’s brainwaves, bringing them to transmigrate into thousands of worlds and experienced many aspect of life in order to stimulate the will of living. Only when the willmeter was filled 100% could they finally return back to life.Lu Yizhou. Male. Single. 22 years old. On a certain day, he committed suicide by burying himself in the land of snow. And then, he was pulled into the simulator.666: Welcome, host! Congratulations, you’re the 666th person who joined this project! Host is very lucky to get 666, because 666 is the handsomest, most sensible and most wonderful system!Lu Yizhou: …Can I change the system? You’re noisy.666: QAQLu Yizhou: No matter how many times I transmigrate, my willmeter will not be filled.666: N—No, don’t give up! Host shouldn’t give up QAQ uwaaa, don’t leave 666 alone! You’re my first, my one and only, how can you be so heartless and leave me behind like this?!Lu Yizhou: …why does it sound wrong?Thus, he started to jump from one world to another to save the villain.Lu Yizhou: Why do I have to save the villains?666: Ckckck, Host you’re too innocent! Of course, it’s because they are more awesome than the male lead; richer, powerful, resourceful, domineering and handsome!Lu Yizhou: …it’s only your preferences, is it?666: Host, why don’t you believe 666?! QAQHe thought that he had nothing left to live for. Bringing with him a weary heart and numb body, he sank to the bottom of the abyss only to find…a shining star.*******Beautiful, stoic, dense and unexpectedly naive gong x possessive, spoilt and scheming shou who knew how to use his charmAdditional tags: quick transmigration, fantasy, adventure, comedy, dark, mystery, tragedy, fast paced, seme/gong/top protagonist, love interest fall in love first, yaoi, mature, suicide thoughts, past play a big part, 1 vs 1

The end of the world is coming, the world has undergone great changes, and everything has changed. Plants, animals, and even insects, as long as there are living things, have mutated.
Become more powerful, and even evolved supernatural abilities, such as chickens and ducks that can fly to the sky, such as cats and dogs that can breathe fire.
But only humans, without any obvious changes, seem to have fallen from the top of the food chain to the bottom of the food chain overnight.
Any creature that can open its mouth to eat can treat humans as food.
But fortunately, this world has not completely killed humans. Gradually, humans discovered that they had the ability to cultivate compatibility with other creatures.
As long as it has a high degree of compatibility with some powerful mutant creatures, it can be used for its own use to achieve the purpose of protecting itself.
Fang He is a person who is very compatible with mutant animals, but it is also because of his ability that he has changed from the strongest to the stupidest.
Fang He, who was reborn, said, “Hmph, this time…”

- Description from novelbuddy