Though, say we finally solve chess. There's not always going to be a "why" the suggested move is the best. There might be heuristics, or even some set of rules

Though, say we finally solve chess. There's not always going to be a "why" the suggested move is the best. There might be heuristics, or even some set of rules in the end game or certain situations that a human's brain can retain to perfection. But for the vast majority of the game, the correct move is what it is, because that's what the computer says, and there's not much more you can do to simplify it. Maybe a good proof golf game would be finding the least computationally intensive proof of tic tac toe or rubics cube or something.