Games as Striped Trees
This video presents the same text shown beside it, spoken and on screen. It adds nothing the text does not say.
State
A two-player game is a tree in which control of the branching alternates: at some forks one player chooses, at the rest the other does.
Show
The root is the current position, one player to move; each branch a legal move; one level down, the forks change hands.
Watch for
The tree is Unit 2's familiar object — the stripes are the only new ingredient.