For Von Neumann, the inspiration for game theory was poker, a game he played occasionally and not terribly well. Von Neumann realized that poker was not guided by probability theory alone, as an unfortunate player who would use only probability theory would find out. Von Neumann wanted to formalize the idea of "bluffing," a strategy that is meant to deceive the other players and hide information from them.
https://cs.stanford.edu/people/eroberts/courses/soco/project...
I learned about Von Neumann and poker from the book "Thinking in Bets" by Annie Duke.
https://www.amazon.com/gp/product/0735216371