Player vs Player mode: Use this mode to keep track of each player's choice and the result. Try changing the punishments for different behaviours and seeing the effect on the game. Player vs AI mode: By default the AI prisoner will choose randomly. In "Retaliator" mode, the AI will always cooperate unless you betrayed them in the last game. In "Random Retaliator" mode, it will usually retaliate, and sometimes it will randomly betray you anyway!
