This is something I have a real love/hate relationship with in Overlord. In the books, we get to see a lot more of what's going on in Momonga's head and how his experience as an average salary worker affects his decisions in his new role as an all powerful lich and the dichotomy of how he perceives himself vs how the people of the world perceive him, which is really cool and fleshes out him as a character and the world a lot more. But then people in the new world will casually throw video game terms into their speech like "putting levels into x class," and it really throws me out of the world.