Join Date: Dec 2008
Posts: 4,653
The doubling cube simply doubles the stake of the game each time. If it is the first double you are now playing for two points. If the cube is turned again it doubles again to four and so on.
If the cube is on two and you turn it again and your opponent does not decide to take it (ending the game there and then) you win the number of points shown on the cube before it was offered to your opponent (in this case 2). If they accept, the game carries on, only now being played for 4 points.
The game then continues until either the cube is turned again, or the game ends naturally (either through bearing off before your opponent or them running out of time), in which case the winner recieves the number of points shown on the cube.
If your opponent runs out of time you should win whatever points the cube is currently on.
Being ahead or behind has no bearing on it.