I watched a video from a guy who used machine learning to play Pokemon and he did a great analysis of the process. The most interesting part to me was how small changes to the reward system could produce such bizarre and unexpected behavior. He gave out rewards for exploring new areas by taking screenshots after every input and then comparing them against every previous one. Suddenly it became very fixated on a specific area of the game and he couldn’t figure out why. Turns out there was both flowers and water animating in that area so it triggered a lot of rewards without actually exploring. The AI literally got distracted looking at the beautiful landscape!
Anyway, that example helped me understand the challenges of this sort of software design. Super fascinating stuff.