zero sum can have any number of players
with genuine respect, SSR, since you seem to be one of the ones who gets the overall concept, you are using a definition you gave in another posting that appears to come from computer sciences.... In the broader game theory definition of zero sum game, there can be any number of participants in the situation being analyzed. People in this thread have used various tournaments as examples (50 people put in $1 and flip a coin, if you flip heads then you advance, if you flip tails you're out, if everyone flips tails the round is replayed, last person gets all the cash, all the losses equal the win, therefore zero sum). While it's helpful in certain computer programming scenarios to break a problem down to two possible outcomes, it's actually a special, restricted case of a broader, eneral concept.
To quote you: it defines the computer science strategy required to play the game (minimax).