Which of the Following Math Classes have you taken?

[True Federalist (진정한 연방 주의자)]

Pretty much everything on the list except topology, but that's because I never got into abstract geometry.  Probably the most fascinating math classes I had back in the day were on information theory.  Number one thing you learn in those is there is no such thing as an unbreakable code.  The best you can do is make it too time consuming and hope no one knows a more elegant and quicker way to decode the message.

[True Federalist (진정한 연방 주의자)]

Is game theory considered a mathematical discipline or an application of probability?

Game theory generally doesn't involve any probability at all. It's an area of applied mathematics most commonly used in economics. The games studied are usually deterministic games where the results depend upon player decisions rather than random chance.