I'm no gamedev, I'm just a curious coder of not-games. I wonder, how does AI work in popular modern games, say, FPSs? Is it based on hard-coded rules? How much does it have in common with other kinds of AI (like the one which powers autonomous cars etc)? How do developers ensure the AI behaves naturally and is fun to play against?
Stuff I've googled mentioned different derivatives of MinMax but failed to answer how AI deals with continuous, changeable world, for what actions/states AI is rewarded and how it figures out its chance for success of different actions. I've also seen Machine Learning mentioned here and there but it seems it's not used in any serious game?