Example:
When playing Monopoly©, if after a considerable number of turns have been taken by each player, and one player gets into trouble, and debt, insead of losing and congradulating the winner, he proposes to "join forces" with another player, shareing money, property, and victory. Tho this joining has no rules set aginst it, this is aginst the spirit of the game, point-and-case monopoly, tho not implicetly stated, is intended to be a 2+player game free for all match to join forces to tip the game in your favor, is aginst the spirit of the game.

Another example would be, if your friends and you are playing Magic the Gathering© and a pact is made between 3 of 4 players to not attack eachother until the fourth has been eliminated, the spirit of the pact would be to kill the fourth in a joint effort, before continueing normal play, the spirit of the pact would be broken if one of the players just builds forces ready to kill the other two as soon as the fourth is dead, tho the pact was not made with this event in mind, the one building forces might not be breaking a specific clause in the pact but it was not made intending to produce an armistice in wich one player can build an unbeatable force, not attacking the fourth was not a clause in the pact but that was the intention, the spirit of the pact.