There is some notation you must know (product, sum, set, etc) but the math is very straightforward, which makes sense, game theory in its most basic form is relatively straightforward logic that one can reason through with needing complex mathematical tools or abstractions.
Ditto on this. Game theory is what people put into practice through play. Any rules more complex than being turn-by-turn decisions or game-length strategy tend to not find their way into interesting models.