When three cards which form a set have been selected they are removed from the board, and if necessary, new cards are added from the deck. The deck consists of 81 cards (one each of each possible configuration of color, number, shape and shading). The game continues until no more sets can be made from the cards on the board. The number of cards displayed varies, depending on the presence of sets, but at most sixteen cards are displayed. Although it is possible to draw 16 cards which do not allow the formation of a set, this is extremely unlikely to actually occur. Thus, the game will most likely end when the deck has been exhausted and no more sets can be made from the cards on the board.
Note: when three cards are selected which do not form a set, they remain selected. Selecting a fourth card will clear them all, or you can deselect one of the selected cards if, for example, you mistakenly chose one of the three.
Improvements which may or may not be forthcoming: