It's also useful for describing a whole range of human interactions. Downside - when you realize people are all cynical fucks, and they all behave in a sub-optimal, selfish way.

It's a branch of maths that formalized a bunch of things and allows lovely proofs for certain interesting settings that economists, sociologists and politologists observe and analyze.

Other than that it currently isn't used that much in computer science.

The key aspect in this case (and many others) is one people usually have a hard time grasping: take in account that your opponent is as rational and intelligent as you are, and can predict your actions just as well as you can predict theirs.

In other words, it's like playing chess against yourself.