One Man and One Shot, I Will Kill All over the World!

The world changes dramatically, and monsters invade. When the human race is in danger, Lu Chen comes through time, awakens the panel, kills monsters and becomes stronger! As a result, he continued to kill demons, his strength increased by leaps and bounds, and he gradually grew into the strongest person in the human race. A few years later, when the demon clan attacked, Lu Chen stood alone on the city wall, facing tens of thousands of demon clan troops, refusing to give an inch of ground. Just one person and one city makes the demon clan flinch.