# Taxonomy of Domino Games, Solitaires and Puzzles

The following taxonomy for domino games, solitaires and puzzles is strictly that of the author [Joe Celko]. I needed an orderly system for putting games, solitaires and puzzles into chapters for a projected book in a fashion which would make sense.

But a taxonomy also suggests new possibilities, by allowing you to ask, "what if" questions in the options chosen in an old game, or puzzle.

## Connecting Games

This what most people think of when they think of domino games. Tile are lay end to end, or end to side according to a matching rule. These chain or trains of tiles form the tableau for the game. We can make a check list of options in these genus of games.

### A) Matching rules

There are only a few kinds of matching rules

1. The ends of the connected tiles must be in the same suit.
2. The ends of the connected tiles must come to some total.
3. The ends of the connected tiles obey some rule.

Method number one is the most common way to connect tiles.

### B) Drawing and boneyard rules

The boneyard is the subset of tiles which are not in the player's hand at the start of a round of play.

1. The "empty boneyard" games have three flavors
1. All tiles are dealt to the players, so there is no boneyard.
2. Tile not dealt to the players are not used in that round, so there is effectively no boneyard.
3. The boneyard is taken out of play when it gets to a certain size. The usual choice is two tiles for Double Six domino set games, but it can be a different number based on the number of players in the game.
2. Boneyard games also have different flavors. A boneyard can be drawn from until it is exhausted. Remember exhausted can mean either there are literally no more tiles left in it or there is only a certain number of tiles left. Boneyard games can allow the following ways of drawing from the boneyard.
1. Players can draw once from the boneyard for their turn when they have no play in their hand. The new tile might be held or played immediately.
2. Players continue to draw from the boneyard until they have a tile which will play in their turn.
3. Players draw from the boneyard until they have replenished their hand back a particular size.
4. Players draw from the boneyard as a penalty or reward for a situation in the game. This includes auctions for tiles.

Games in which there is no boneyard are usually called Block games and those with a boneyard are called draw games for obvious reasons.

### C) Spinners

A spinner is a double which is turned sideways in the line of play. It has the additional property that other tiles can be played from its two exposed ends and its open side. A connecting game can have:
1. No spinners
2. One spinner
3. All doubles are spinners

A spinner can grow a certain number of arms:

1. One arm (i.e. it acts like a regular tile)
2. Two arms
3. Three arms (the most usual case)
4. Multiple armed spinners (the largest case is about eight)

### D) Scoring

Points can be scored for:

1. Going domino (i.e. getting all the tiles out of your hand)
2. Making certain combinations with the ends of the arms of the tableau.
3. Making certain totals with the ends of the arms of the tableau.
4. Tiles left in the hand are giving negative points, usually based on the total number of pips on the tiles.

Virtually every possible permutation of these options has been used in a connecting domino game.

## Meld and Combination Games

Certain combinations of tiles score points, without any concept of connecting the tiles. These are games derived from card games like rummy, poker or blackjack. Many of the Chinese games are in this family and the king of these Asian tile games is Mah Jong.

We can break this family into melds and totals:

### A) Melds:

A meld is a pattern derived from the suits and suit ranks involved. The most common melds are:

1. Sequences within a suit (usually three or more tiles)
2. Sets of doubles (usually two or more)
3. Sets within suit (usually three or more tiles)
4. Special pairs (see Pai Gow)
5. Other combinations

Melds can either have point value in themselves, be ranked against each other or can be used for meld-trick games. Most Western games in this family are point meld games, such as the Rummy family, and ranked meld games, such as the Poker family.

Asian games favor the meld-trick family for both card and domino games. In a meld-trick game, melds are ranked and are played as if they were single cards in a trick taking game. The highest meld wins the trick and captures the other melds played against it.

### B) Totals:

Tiles are captured or scored based on their total pips. Again, the use of totals seems to be more popular in Asian games than in Western domino games.

## Trick Taking Games

The scoring is determined by capturing tricks. A trick is round of play in which each player contributes one tile. The winner of the trick is the player who placed the highest ranked tile. Exactly how the tiles are ranked can vary from game to game, but usually in Western card games this mean that you have to "follow suit" or "play trump"; some Asian card games allow you to play any card you wish. To "follow suit" means to play a tile in the same suit as the first tile lead on the trick. To "play trump" (from the French word for "Triumph") means to play a tile from the suit which has been declared trump; all tiles in the trump suit outrank all non-trump tiles, but are still ordered within their own suit. The trick games break down into

1. Simple trick games, in which all tricks are score alike.
2. Point-trick games, in which certain tiles have point values when captured in a trick.
3. Auction or contract games, in which a partnership or individual player bids make a certain number of tricks or points.
4. Meld-trick games, in which certain combinations of tiles have point values either in the player's hand or when captured in a trick. In a meld-trick game, melds are ranked and are played as if they were single cards in a trick taking game. The highest meld wins the trick and captures the other melds played against it.

## Miscellaneous Games

The nice part about having a miscellaneous category is that you have the feeling you have covered and classified everything.

## Solitaire Games

Solitaries all involve moving tiles from a hand thru a tableau to "the Aces", or a discard area. A game is successful when all the tiles are thus transferred to the discard.

Solitaries can be classified by how the tiles move from hand to tableau to discard:

1. The tableau is based on connecting rules and also serves as the discard. The goal is to domino your hand.
2. Total Solitaries: Tiles are discarded when they reach a certain total.
3. Pattern Solitaries: Tiles are discarded when they form certain patterns on the tableau. These games often start with all the tiles in the tableau.

Most solitaire games can be modified to allow more than one player, if they include a hand and a tableau. Each player gets his own hand to play against the tableau. A player either continues to add to the tableau and discard either one tile per turn or until he is blocked. The game is won by the first player to domino.

## Domino Puzzles

Domino puzzles can depend on either the shape of the tiles or on their pips. The puzzles based on the pips can be either based on connecting tiles or on the totals of the pips.

Among the puzzles based on just the shape of the tiles, the most famous is the "Dominoes and Checkerboards" family. The puzzler attempts to place dominoes on a grid of squares, and only the shape of tiles matters.

The connecting puzzles usually provide a tableau without any of the pips on the tiles shown and the puzzler attempts to place the tiles in that pattern using the rule that ends that touch must be in the same suit.

The totaling puzzles are provide a tableau without pips shown, but the goal is place the tiles in such a way that certain totals appear in the rows columns and/or diagonals of the tableau, without regard to a connecting rule for the ends.