In the World of Sword and Magic as Space Marine - Chapter 41: Relationship Problem

Monsters, both human and beast, surrounded him. He needed power to survive this new world... but he arrived as a mortal.One moment William was at work. The next, he was captured by lunatics.He had never believed in the fantastical, but he had no choice after finding himself in another world surrounded by demonic cultivators trying to extract his soul. If he couldn't find an escape, his journey would end just as abruptly as it started.William was inches from death when a benevolent cultivator saved him from that fate. Seeing his pitiful state, the cultivator decided to give him an opportunity in the form of a tool: A system to guide him on the path of cultivation.William would use it to claw his way to the peak of the cultivation world.

Dante was an ageless warlock who had been going from one battle to another for hundreds of years.Following a chaotic encounter with an evil god, Dante unintentionally activates a contract with a demon, thrusting him into the modern world.Resolved to live a peaceful life, his intentions are halted when he finds himself in the middle of a conflict among rival mafia factions—dabbling with the ominous demonic magic that he knows best.

This is a story about the protagonist getting the system, going crazy in the biochemical apocalypse, producing aircraft and tanks, destroying zombies, saving good people and killing bad people.

- Description from novelbuddy