Several months ago I came across a really cool vintage 1940 copy of Hoyle's Complete and Authoritative Book of Games book. I'm not sure how games are played in your house but when I was growing up there were different rules for the same game depending on whose house you were playing the game at.
This "authoritative" book sure would have come in handy to solidify official rules! I don't know how you feel about allowing three of a kind sets in the game of Rummy, but I think it should be banned, except for sets of Aces, of course! But I am all for landing on Free Parking in Monopoly meaning you win the center pot of money, even if that is not the "official" meaning.
Dominoes glossary of terms:
Bones: The dominoes, also called tiles, rocks, or stones.
Boneyard: The dominoes left after all players draw their hands in the scoring and matching domino games. Set: The first domino played in a hand.
Cutthroat: Any domino game in which each player plays independently, with no partner. This term denotes that each player is out to beat the others.
Here is an interesting version of the game from this book.
Two players draw seven bones each. Highest double sets (plays). If neither has a doublet, the heaviest domino sets. There are four trumps, or matadores. These are the double blank, and the dominoes that have 7 pips on their faces; the 3-4, 2-5, 1-6.
Doublets are not set across the line, a doublet being no better than a single number. The object of the game is to make the ends of the adjoining dominoes, added together, equal 7. If a player cannot do this, he must either play a trump or go to the bone-yard and draw until he can make a seven or get a trump. The last two bones must not be drawn.
When a trump is played, the player can expose whichever end of it he pleases by placing it crossways, so that the next player will have to make a 7 by playing the complement of the exposed end.
Image Sources: Willow Bee Inspired, Watson Kennedy