This game is a member of the Fives Family, a West Coast version of Seven-Toed Pete in which all the doubles are spinners. It is described in Dominic Armanino's 1978 book Dominoes: Popular Games and Strategy under the title "Race Horse (Seven-Toed Pete)" and a commercial version "RaceHorse" using a double six set with digits on their faces instead of pips was published by Ferman C. Rice in 1990.
The game uses a double six domino set. The game can be played by two, three or four players; four may play as partners. A cribbage board is useful for scoring, since scores are totaled as they are made and not at the end of the hand.
The first player in the first hand is determined by lot. In the following hands, the player who dominoed in the previous hand plays first. If the last hand was blocked, then the lead is determined by lot again. The lead can play any tile in his hand. The next players must match the ends of the tiles on the table.
All doubles are played as spinners, and are placed across the end to which they are added. They count as the total of their pips on both exposed ends for scoring purposes.
When a player sets a double or a tile that scores (see below), he gets to set another tile in his turn. He continues to add tiles to the tableau until he sets a tile that does not score and is not a double. The turn then passes to the next player.
If a player cannot play a tile, he must draw tiles from the boneyard until he has a tile which will play or the boneyard is empty. When he draws a tile which will play, it goes on the table immediately and his turn ends (even if it is a double or scores). If he empties the boneyard and still cannot play, he passes and the next player takes his turn.
The hand continues until one player dominoes or until all players are blocked. An empty boneyard does not stop play.
After a player has set a tile, the arms of the layout are totaled. If this total is a multiple of five (5, 10, 15, 20, and so forth), the player immediately pegs that total divided by five - for example 4 points for a total of 20. Remember that an exposed double counts as the total of its pips. For example the [5-5] counts as ten pips on the end of an arm. When a second tile is played on a double, it is added to the free side (not an end) and the double then ceases to count towards the pip total.
The player who dominoed, or the player with the lowest total pips if the game is blocks, is the winner. This player pegs the total pips in the other players' hands rounded to the nearest five and divided by 5. If two players tie for lowest in a blocked game, they both score.
The game is played for 61 points, making a cribbage board very useful.
Joe Celko describes a slightly different version of this game. When a player who is drawing from the boneyard finds a playable tile which is a double or scores, his turn ends - he does does not take an extra turn. Players who score for making a multiple of five, score the full amount - the scores are not divided by five. When the hand is finished, either by being dominoed or by being blocked, the pips on the tiles remaining in each hand are totaled. Instead of the winner scoring the total of the opponents' scores, each player (including the winner of a blocked game) subtracts the number of points remaining in his hand, rounded up or down to the nearest five points. With these larger scores, the target score for winning the game should also be higher - perhaps 200 or 250 points.
One player can surge ahead with a string of plays in his turn and unexpectedly domino or surge ahead of the other players. You might want to save a chain of tiles for just such a surge.
As in any domino game, the player who can count the outstanding tiles has a strong advantage.
Beginning players have trouble doing the required math in their heads. They will tend to think in terms of arms which end in 5, instead of looking for other combinations that give a multiple of five. Also, beginners do not think of reducing the previous total to a multiple of five.