The gameboard is a circle divided into four areas. Each player has one area where he tries to achieve certain combinations of stones while avoiding others.
Each round you put two stones in your hand. Stones in your right hand will turn the gameboard (so you can "steal" areas from your opponent), stones on the right hand will be put on the board.

The title refers to the turning of the gameboard and the placing of the stones (dark stones always go on the left, light stones to the right side of the board)