hide in the banished palace and level up to a big boss

Hiding in the Cold Palace and eventually becoming a Boss of Sorts
Li Mu was transported to a fantastical world and became a measly eunuch of the State of Xia. Despite having initially thought that his life would be a miserable one, he had unexpectedly acquired a check-in system.
Ding, successful check-in at the cold palace. ‘Zaohua Sutra’ acquired.
Ding, successful check-in at the Imperial Dispensary. Xiaohuan Pill acquired.
Ding, successful check-in at the Library Tower. 50 years’ worth of power acquired.
…
He had initially thought that the world would be a dangerous one, and that he would never venture outside without first becoming the most powerful combatant in the world.
However, riots taken place at martial art sacred grounds 60 years later, and countless formidable ones attacked the Royal Palace of Great Xia…