Overwhelming Firepower - Chapter 9: Arquebus

Humanity’s home is no longer Earth. Intersellar travel is now a common occurence, and technology has replaced blood and flesh.Luka, who grew up in the slums, has turned fifteen and taken the selection exams. His aptitude is of the “Imperial Guard.”

Gawain is dead and was transmigrated, but there was a slight problem during the process.
After floating for more than a hundred thousand years on a different continent, he felt that he might need a body to become a complete transmigrator, but he did not expect that…

- Description from Novelupdates

Cui Heng was transmigrated to another world and the system told him that the new world he was in was a high-grade Xianxia world.

In a world where martial artists reign supreme, strength is everything. Unfortunately, that logic doesn't apply to a certain Florida Man.

Refined in the nuclear fallout wasteland, Leo was the strongest mutant alive. He carried an alien artifact, allowing him to exchange his lifespan for modern items. After 50,000 years of solitary life in a humanless world, he collected enough lifespan to transmigrate to another habitable world.

Leo was later thrown into a mysterious planet. He soon discovered that his body produced radiation, and it mutated the surrounding plants and grasses. Worrying that he might ruin the beautiful planet, he chose to live in seclusion.

Unfortunately, the local population soon discovered his existence, and a misunderstanding ensued.