The deck
Fifty-five cards, one for every double-nine combination from 00 to 99. Each card has a top number and a bottom number, just like the two halves of a tile. The small numbers in the corners tell you what the card is without turning it around. A double is a card with the same number on both halves. There are ten of them.
Players and teams
The classic game is four players in two partnerships. Partners sit opposite each other. You never show your partner your cards or talk about them. That is what the table talk is for.
The deal
Shuffle ("dale agua"). Deal ten cards to each player. The fifteen cards left over are set aside face down. They are out of the hand. Nobody draws from them, and nobody peeks. Not knowing which fifteen are asleep is half the game.
Hold your cards like a card hand. Read the corners.
The opening (la salida)
Only the first hand needs a decision, and tables decide it a few different ways. Pick one before the deal.
Draw for it. Before the deal, one player from each team (or every player) pulls one card from the shuffled deck and shows it. The highest total opens. The cards go back before dealing. This is the most common way in Cuba and Miami.
La Gorda opens. After the deal, whoever holds the 9|9 plays it to open. If it is asleep in the fifteen, the highest double at the table opens instead, or the deal is repeated.
Highest double. After the deal, whoever holds the highest double opens with it, whatever it is.
Whatever the method, the opener may lead with any card. Leading with a double is traditional, not required.
In every hand after the first, whoever won the last hand opens the next one, and may open with any card they like. What they choose to open with is the first message of the hand.
Playing a card
Play moves to the right, counterclockwise. On your turn, play one card so that one of its numbers touches a matching number on either open end of the line. A 5|2 can go on an end showing 5 or an end showing 2. Doubles are laid across the line, the way you would lay a tile.
Keep the line on the table so everyone can see both open ends. When it gets long, bend it.
Passing (el paso)
If you have no card that matches either end, say "paso" and the turn moves on. You may not pass if you can play. Passing is information: everyone now knows you are missing two numbers, and a good partner will use that.
Ending the hand
A hand ends one of two ways.
Dominó. A player plays their last card ("me pegué"). Their team wins the hand.
Tranca. Every player still holds cards but nobody can play on either end. The line is blocked. Each player adds up the numbers on the cards still in their hand. The player with the lowest total wins the hand for their team.
If the two lowest totals belong to opposing players and they tie, most tables call it a draw: nobody scores and the same player opens again. Agree on this before you start.
Scoring
The winning team scores the total of all numbers left in the two opponents' hands. A 6|4 left in a hand is 10 points. La Gorda is 18. La Blanquita is 0.
The first team to reach 100 points wins the game. For a longer night, play to 150 or 200. Decide before the first shuffle.