Games are described by positions. In the normal play , the player with no options whose turn it is to move is declared a loser. So that in the game 0, the second player to move is a winner. Regardless of who starts, Left wins the game 1, while Right always wins the game -1. In general, a game is negative, positive, or zero, depending on whether Left, Right, or the second player has a winning strategy.
Some games are neither.
The theory and practice of mathematical games often force the players to play several games simultaneously. Games can be compared. Numbers are defined inductively as those games P whose options are numbers with an added condition that no left option is greater than or equal to any right option. The adopted notations reflect on the value associated with a game. Thus, for example, the game 1 is greater than the game 0.