The logical dominoes represent a puzzle you will have to solve in two minutes! The chips that are deprived of the separating line are put on the board in a form of a rectangle. You have to restore the original chips or form new ones. For that you should left click on the first half of the assumed chip and release the button only when the cursor is on the second half. If you are right with the chip and there are no more chips on the board identical to it then it appears on the board.