In a Troubled Era, How Did My Father-in-Law Don the Yellow Robe?

Chen Wenluo wakes up after a single sleep and finds himself transported to an ancient imperial dynasty, becoming a sixty-year-old man in a tumultuous era. None of his five sons are reliable—some have run away, some have starved to death, and one foolishly dreams of joining the army to serve the country. Only his five pitiful daughters-in-law remain, relying on him, their father-in-law. Life is hard, debt collectors come knocking, and the family is miserable with no way out. Unexpectedly, an entry-binding system activates: increasing intimacy activates entries, which can be upgraded infinitely. [Strong and Healthy] upgrades to [Rejuvenation]. [Hundred-Step Piercing] upgrades to [One-Hit Kill]. [Strength of an Ox] upgrades to [Nine Oxen and Two Tigers]. The sixty-year-old man instantly becomes an unparalleled hero. He hunts and fishes in the deep mountains to make a fortune, and his fame as a tiger-slaying hero spreads far and wide. Just as the troubled times grow chaotic, the sixty-year-old dons armor and mounts a horse, contending for the realm. When his sons return, they are all dumbfounded. "Dad, how did you carve out territory, become a king, and aim to dominate the world?" — Description from novelcodex.org