Zero-Sum Game
Poker and gambling are popular examples of zero-sum games since the sum of the amounts won by some players equals the combined losses of the others. In game theory, the game of “Matching Pennies” is often cited as an example of a zero-sum game. ... This is a zero-sum game because one player's gain is the other's loss.
Zero-sum is a situation in game theory in which one person's gain is equivalent to another's loss, so the net change in wealth or benefit is zero. A zero-sum game may have as few as two players, or millions of participants. Zero-sum games are found in game theory, but are less common than non-zero sum games.
In contrast, non-zero-sum describes a situation in which the interacting parties' aggregate gains and losses can be less than or more than zero. A zero-sum game is also called a strictly competitive game while non-zero-sum games can be either competitive or non-competitive.