Object of the game: To discard all the tiles in the set two at a time, in pairs, when pips total 12.
Draw 6 tiles from the deck and place them faceup in a horizontal row in front of you.

If any two tiles in your tableau together have pips totaling exactly 12, remove those two tiles from your row and set them aside. Then, replace them by drawing two more tiles from the shuffled deck. Continue to do this, and win the game by discarding every tile in the deck.

If the situation arises that there is more than one pair of tiles whose pips total exactly 12, you may discard each and every pair of tiles before replacing your tableau with more tiles from the deck.

If a tile's pips can be added to more than one other tile in the tableau to get a total of 12 pips (for example: a 3-3 can be added to the 6-0 to total 12, or the 3-3 can be added to the 2-4 to total 12), you may discard any pair you choose.      

Variations: 1) Use a tableau of 5 tiles for a more difficult game or a tableau of 4 tiles for an even more difficult game. You may also increase the number of tiles in your tableau to 7 for an easier game. 2) With adjustments, this game can be played with a set of dominoes other than the double-6 set. When playing with a double-9 set, the pips on two tiles in the tableau must total 18 in order to be discarded. The game may be played in this way with any set of dominoes. Just take the total number of pips on the highest tile in the set (for example: 6 for a set of double-3 dominoes; 24 for a set of double-12 dominoes) and that is the number that two tiles in your tableau must total in order to be discarded.

Variation: In the regular game, the 0-0 and the 6-6, and the 1-0 and the 6-5, must be matched to make 12, because there is no other way to match them. For the other tiles there are at least two ways each tile can be matched. Therefore, the 1-6 can be matched with the 4-1, 2-3, or 0-5. The game becomes much more difficult if you limit more of the tiles to only one possible match each.

Try this variation: Require that each of the ends of the matching pair must total six.

The four remaining tiles (0-6, 1-5, 2-4, and 3-3) are tiles with 6 pips each and cannot be matched to another tile in the set so that the ends of the matching pair of tiles would total six. Therefore, the requirement that the ends of the matching pair of tiles total six will not apply to these four tiles; each of these four tiles may be matched with any one of the other three tiles to make a total of 12 pips for the pair, as in the original game.