TAG is a fine old game, a perennial favorite. It can be played with only two, and often is, among siblings. Otherwise, the contest goes on until something or somebody calls a halt.
The point of this exercise is Fatigue, generated by frantic running and ducking and dodging. Also swiveling.
Assuming the Taggee gets away from the pursuer, the rest of the time is spent panting. Or, if caught, that player becomes It!, and the merriment continues…
