Tariffs are pretty easy to explain.
You know the whole prisoner's dilemma thing? if you both cooperate it works out well; if one of you screws over the other, you benefit and they suffer; but if both of you screw each other over you both suffer worse?
Same shit, but for economies, and with the guarantee of tit-for-tat.
@robryk
Sort of, but only inasmuch as the other players in their own parallel games get to see what your strategy is and treat you accordingly.
The US picking a trade war with China, for instance, would be an iteration that other players will study and determine who they would benefit from.