Return of the Swallow - Chapter 526.1: Battle Tactics

A skilled but unfortunate modern-day assassin was killed in a freak accident. However, he soon found himself summoned to another world by an evil wizard, who had him possess the body of a boy as an experiment. After successfully planning the evil wizard’s downfall, he used the wizard’s body as a springboard to gain influence and power in his new world.

- Description from Novelupdates

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

Aldric, a young man from a remote village who doesn’t know much about games is forced by his dorm mates to play the latest and most popular virtual reality game — Magician Online, a magic-themed game with a magnificent medieval world. Armed with curiosity, he played the game without serious intentions. However, unbeknownst to him, he actually awakened the most supreme talent in the game.

Orphaned at a young age , Layla Llewellyn feels like the luckiest girl in the world after she moves in with her uncle Bill , a gardener who lives on the scenic Arvis estate in the Berg Empire . To Layla Arvis seems like paradise ; she loves to explore the vast forest , always bringing her notebook to record the wildlife she encounters . She especially loves the birds , watching them with awe as they hatch and grow from fluffy chicks into beautiful birds . Duke Herhardt , the young , handsome lord of Arvis , is also interested in birds--- and Layla . But the difference is , he's interested in birds because he likes to hunt them.... and he's interested in Layla because he likes to make her cry . If a lovely bird is trapped in a golden cage , which will she choose : a life of luxury , or freedom ?