The objective is to change the coloured squares in the 6 x 6 board.
Roll 4 or more marbles of the same colour next to each other to remove them. The squares under the disappearing marbles will change colour. A board is solved when all its squares become grey, then you can move on to the next board.
A context menu should be shown when right-clicking or, on touch devices, long-pressing in the game. This menu especially allows to play in full screen and control the volume.