Scientists disagree about when, if ever, life on Earth might be representative of life everywhere it might arise. This topic, universal biology, the study of life as it must be, is among the most thought provoking (and overwhelming!) issues in philosophy of science. Biology spans huge temporal and spatial scales, from milliseconds to millennia and from bacteria to biospheres. Accurately representing even a portion of this scale requires a level of abstraction that is agnostic to physical configurations or particular biochemistry. In this presentation, I argue that the insights and methodology of evolutionary game theory are crucial to developing a robust, rich, and fascinating universal biology. Several core ideas in evolutionary game theory can be instantiated by many different systems and are agnostic with respect to contingent biological history and structures. I show how game theoretic methods apply to the origins of life, evolutionary dynamics in astrobiology, and guide potential future lines of inquiry. In sum, game theory is a missing perspective to helping us understand life not as it is, but as it must be.