The goal
Dominoes here is a partnership game. You and the seat across the table play as a team against the two seats beside you. A hand pays the winning team the pips still sitting in the opponents' racks. The first team to one hundred wins the match.
The deal
Four seats, and your partner is the one facing you. Play moves clockwise around the table, so the two seats beside you are your opponents.
All twenty-eight tiles are washed and dealt, seven to each seat. Nothing is left over. There is no boneyard to draw from, so a seat that cannot play must knock.
There is no dealer. The only asymmetry is who plays first, and that seat is the setter. Before the first hand every seat draws one tile face up. The heaviest sets (at equal weight a double wins, then the heavier end). The tiles go back, the set is washed, and the setter opens with any tile. After that the seat that went out sets the next hand. When a hand is blocked, the lightest rack sets; partners tied for lightest send it to whichever of them comes first clockwise from the last setter. When nobody wins, the set passes to the seat after the previous setter. A host may choose Double six opens (never in ranked play). Then there is no draw: whoever holds the six-six sets the first hand and must open with it.
The play
The line has two open ends. On your turn, lay a tile whose value matches one of them. A double is laid across the line, but it still shows the one value at that end. The first tile opens both ends of the line. A double set first opens both ends on the same number. The line only ever has two ends. A double is never a spinner, nobody draws, and nothing scores during play.
If no tile in your rack matches either open end, you knock and the turn passes. A knock is forced, never chosen. You cannot knock while you hold a legal tile. Every knock is public, and it is the only thing you can tell your partner: it says you hold neither of those two values.
Seven tiles carry each number. Count what has been played and you know what is still out, and who may be holding it. Shed heavy tiles and doubles early. A blocked hand pays the lightest rack, and a double fits half as many places as any other tile. Every knock tells the table which numbers that seat lacks. Keep your partner's numbers open, and close the ones your opponents need.
Scoring
A seat that plays its last tile goes out, which is the domino, and ends the hand at once. The winning team scores the pips left in the OPPONENTS' racks. Your partner's tiles cost you nothing. A tile is worth both its halves: a blank is nothing and the six-six is twelve. A hand pays the exact pips, never rounded.
When four knocks come in a row, the hand is blocked and nobody has gone out. The lightest rack wins the hand for its team, which again scores the opponents' pips. Partners tied for lightest win it together. If the lightest racks are tied across the two teams, nobody wins the hand and neither team scores.
Winning
Hands are played until one team reaches the target. A match takes several hands. At a nearby table a seat that drops is held for 30 seconds. After that the game ends for everyone.
