Chess, sometimes also known as international chess, is a board game and mental sport for 2 players. In chess, when a king is directly attacked by one or more of the opponent's pieces, the player is said to be in 'check'. When in check, only moves that can evade or block check are permitted. The object of the game is to checkmate your opponent, this is when their king is in check, and no move can be made that would escape from check. Chess is not a game of chance; it is based solely on tactics and strategy.