A game in which the players are all friendly towards one another, or are not playing for any gain, for example: a friendly soccer game would imply that its either a game played with your friends down the park, or that its a game played by professionals, but there are no league points or cup to win, it is a game for its own sake.

Most sports have some form of friendly game. And most non-sport type games by their very nature are friendly.

In poker there is no such thing as a friendly game.