First, the math: if you can handle integers 1, 2, 3, and 4, and can deal with 'greater than' and 'less than' relationships, you've got all you need. "I'm not a math person" is no excuse. Second, the relevance: Brams touches on examples from Samson and Delilah, to the Nixon tapes, to Macbeth, to Abraham and the Old Testament god, to the American civil war, to Catch-22. Just about every interaction between to two agents, each seeking benefits of their own, can be phrased in these terms.
Most importantly: why bother? I mean, literary analysis has been doing quite nicely all these years without it. And doesn't all that mathy stuff deaden the real emotional impact of a story? Absolutely not. Personal drives, motivations, and goals form the critical inputs to these analyses. This offers a framework for playing one actor's urges and preferred outcomes against the other's. There's no assumption of an economist's insanely rational agent acting with perfect knowledge, just real people (or other beings) with things they want and things they want not to have happen. Then with just a little thought about each character's available options and desired results, this analytic framework shows why the two interact as they do. It shows how each can change their interaction, and whether they should. If you've ever had the feeling that some fictional characters just aren't behaving realistically, this can show why. Or, if a character acts in unexpected ways, game theory can suggest where to look to see what the reader has missed in undestanding the motivations. And, since we're dealing with basically subjective feelings, preferences, and choices, game theory offers a range of alternative analyses. Once you see how the characters stand, relative to each other, you can try out different ideas about their motivations until you come up with an understanding that explains the action as it stands. Even threats and bribes fall neatly into the basic framework.
Human (and other) interactions hold endless complexity. Each one has its outcome, though, or evolving series of outcomes. And, at a high enough level, there are only so many broad categories of outcomes. Putting a name to that outcome does nothing to reduce its drama, joy, or pain. Instead, it can deepen a reader's appreciation of how it came about, and what made that outcome inevitable (if it was). Rational thought and real feeling aren't opposites. This book shows how rigorous logic can help in understanding unique personalities and how they work together - or don't.