A decision tree (the entirety of my game theory experience has been a few online videos, so I likely have the terminology wrong), with decision 1 at the top and the end outcomes at the bottom. The sections marked 'max' have the decider trying to pick the highest-value end outcome, and the sections marked 'min' have the decider trying to pick the lowest-value end outcome. The numbers in every line except the bottom propagate up depending on which solution will be picked by whoever is currently doing the picking, so if Max and Min maximize and minimize properly the tree's value is 6. I don't quite remember how the three branches being pruned off work.