Iron Blooded - Seventeen: Without Mercy

Have you often come across a game where you start with a bonfire, surrounded by ice and snow, with resources all manually transported, and monsters attacking at any time...Xia Hong wakes up to find himself in such a world.The ice and snow rage on, beasts rule the land, civilization is lost, and all people and things that once existed have been invaded into powerful and bizarre entities, leaving humans as a humble race surviving in the shadow of winter, on the brink of extinction.Fortunately, Xia Hong possesses a camp system that can upgrade infinitely.[Small Bonfire]—[Iron Furnace]—[Solar Cauldron]...[Wooden Post]—[Training Ground]—[Martial Arts Hall]...[Bamboo Fence]—[Black Soil Wall]—[Iron Wall]...[Monument Stone]—[Notice Board]—[Hero's Monument]......As Xia Hong slays the beasts and exterminates the bizarre entities, gradually gathering humans, dispelling the winter, and opening up territory, the mysterious veil of this world is slowly unveiled in its entirety.

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

Merged into the body of External Disciple Chen Yu was the heart of a demonic god.The heart is the core of life, the most fragile vital organ. To Chen Yu, however, the heart was his greatest strength, granting him power and potential beyond demonic and divine beasts. Here on out, we follow him as he embarks on a mysterious and wonderful journey.

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