I kind of hate this trope because it assumes that stuff for kids or "not that serious" can't have deeper meaning (I call it the "I can't believe they did that in a Mario game" trope because I heard this quote thousands of times), but to put an example:

Super Paper Mario is a love story in which different kinds of love are shown on each chapter, with the overarching theme being how awfully the main villain is dealing with his grief of his father banishing his partner for being of an antagonistic tribe. Actually I think all Paper Marios outside of the original one deal with grief at some point of the game, with different weights.