Backgammon is a classic abstract strategy game dating back thousands of years. Each player has a set of 15 "men" that must be moved from their starting positions, around, and then off the board. Dice are thrown each turn, and each player must decide which of his men to move based on the outcome of the roll. Players can capture each other's men, forcing the captured men to restart their journey around the board. The winner is the first player to get all 15 men off the board. A more recent addition to the game is the "doubling cube", which allows players to up the stakes of the game, as it is often played for money. Although the game relies on dice to determine movement, there is a large degree of strategy in deciding how to make the most effective moves given each dice roll as well as measuring the risk in terms of possible rolls the opponent may get.