The Warden of The Witches - Chapter 14:

Shiao Yi is an 18 years old boy from a war-torn future, he is badly injured while escaping his enemies and wakes up in a strange, old-fashioned world with no technology—only magic, swords, and monsters.He’s saved by a kind but mysterious knight named Dominic and taken to a stone fortress where people think he’s just a lost child.As he heals and tries to hide who he really is, Shiao Yi slowly realizes he may have ended up in another world.With no idea how he got there or if he can ever return, he must learn to survive, understand magic, and figure out if this strange new place could be his chance to live a real life—for the first time ever.

Ruins stretched across the landscape in the apocalypse after the nuclear war.

Turned into a vampire with no political backing, wealth, or power, Dylan immediately tries to become the strongest there is. Facing numerous dungeon breaks and a coming invasion of unknown origin, Dylan must do everything he can to fight back. In the process, Dylan tries to make the world a better place in his way, by taking control of as much land and women as he can. Watch as Dylan amasses power and influence among monsters and humans and rises to the top in more ways than one.

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.