There are many approaches to game design, but the most common ones are two: “theme -> mechanics” and “mechanics -> theme”.
Sid Meyer is one of the most famous representatives of the “theme -> mechanics” approach. In that fashion, you start from a fantasy, an experience you want to offer to the Players. Then you describe all the mechanics needed to realize that fantasy. Mechanics should offer meaningful choices for the theme to be properly implemented.
Shigeru Miyamoto is a master of the other approach, mechanics -> theme. His games try to find the most engaging and fun mechanics with lots of possibilities. Those games offer surprising twists, using a Japanese technique inherited from drama: kishotenketsu. The mechanics define new in this way new themes. If you look at the most famous games, the theme sounds pretty crazy. It’s because it is defined by mechanics, not the other way around.
What about us? Should we choose one approach and go for it or look for a synthesis? That is up to you, to me the important thing is to be aware of our choice and not leave it to chance.