According to Jesse Schell, author of The Art of Game Design: A Book of Lenses, a resonance is the quality of a game's theme that "touches players deeply," makes an impact (53). To Schell, there are two types of resonant themes: experience-based themes and truth-based themes.
Experience-based Themes are resonant with players because they fulfill player fantasies and desires in some way. Schell uses the example of his work on Pirates of the Caribbean: Battle for Buccaneer Gold, a virtual reality experience in a Disney park. The "fantasy of being a pirate," according to Schell, is powerful not only because nearly everyone has had it at some point, but because "it resonates with our desire to be free [...] do what we want, when we want to" (53).
Truth-based Themes are resonant with players because they affirm deeply held personal beliefs of the people who play the game. As an example, Schell uses the plot of The Titanic. It may have had great production values, but the reason it was so successful was because everything adhered to the resonant theme of "love is more important than life, and stronger than death," in Schell's words (53). Great games (or any form of media) tap into themes like this in order to make an impact on their audience.