# Dominos

## Introduction

There are numerous games in many variants using different kinds of dominos. There are also many different dominos sets available, suited for several usages.

The most popular and used set is still the double-six set, having 28 pieces in total, containing:

- A unique piece representing every possible couple of two numbers between 0 and 6 respectively: 0/1, 0/2, 0/3, ..., 0/6, 1/2, 1/3, ... 1/6, 2/3, ... 5/6
- Seven « doubles » for which the two shown numbers are identical: 0/0, 1/1, 2/2, ... 6/6

One can also rather easily find double-nine and double-twelve sets having the same distribution but for numbers between 0 and respectively 9 or 12. These larger sets can accomodate for a greater number of players, because the classic double-six set can only up to 4 players. The total number of pieces for a defined set of dominos is given by the formula (n+1)!/(n -1)!/2 +(n+1), where n is the greatest number found in the set. For 6, it gives 7!/5!/2 +7 = 5040/120/2 +7 = 21+7 = 28.

Dominos game rules are numerous and have been invented in many parts of the world across centuries. The following rule, which is the only one applied on the playroom, is only the very basic rule, smallest common denominator between all existing rules. But many players created their own variants, putting conditions on placing options, changing layouts, or giving special features to particular pieces.

## Game rules

At the beginning of the game, the dealer deals between 5 and 7 pieces to each player, depending on their number and on the set used. Remaining pieces form the draw pile, which we more commonly call *boneyard* when talking about dominos, because they are normally inside a black and thick bag that prevents cheating. When playing with 4 players and a double-six set, everybody gets 7 pieces and there is no boneyard.

After the distribution is finished, each player plays one after the other in turn, starting with the one having the largest double. In case it's in the boneyard, one can start with doubles smaller in value. The goal of the game is to be the first one to get rid of all your pieces, so that you get a minimum of points.

The first player must put a double at the center of the table. Then, at your turn, you will have to put, next to already placed dominos chain, a piece on which one of the two shown numbers corresponds to the one on one of the two ends of the chain. For example if we have the chain 1/2 2/5 5/4 on the table, you can play a domino 4/6 to the right, so that the chain becomes 1/2 2/5 5/4 4/6, or you can also play a domino 1/3 to the left by turning it, so that the new chain would become 3/1 1/2 2/5 5/4. If you don't have any playable piece, you must pick one in the boneyard. If you just took a playable domino, you can play it immediately. Otherwise you must keep it in your hand, and it's the next player's turn. If the boneyard is empty, you just skip your turn.

Sometimes, it's possible that a particular piece can be placed at both ends of the chain. In this case, you can remove the ambiguity by pressing D for right or G for left to indicate where you want to play .

The round finishes when someone has no more dominos in his hand, or when the game is blocked so that nobody can play anymore. One considers the game to be blocked when a complete turn around the table passed with nobody being able to play and when the boneyard is empty.

### Scoring

The player who ends the round doesn't get any point. Other players count the dominos they still have in their hand. Each piece is worth the sum of the two numbers shown on it, except for the double 0 valued 10 points in case it's the only one you have. If the game ends blocked, all players count their remaining dominos.

The objective of the game is therefore to get as few points as possible. On the playroom, one defines a score limit and all players reaching it are out of the game. The winner is the last player staying in-game. This limit is proposed to 100 points by default.

### Team play

It's possible to play dominos in teams. In this case, players are positioned so that the turn of each team is correctly alternated. The playroom allows to play dominos individually or in teams up to 10 players, forming 2, 3, 4 or 5 teams of 2, 3, 4 or 5 players each.

The player who wins a round makes his team not collect any points, while players in opposing teams sum up their dominos. Dominos that remain in the hands of the winning team are counted as penalty added to all other teams' scores. This is not standard, but it allows a little more strategy. Just like in individual games, all the teams get points when the round ends blocked.

## Keyboard shortcuts summary

- Space: draw a piece from the boneyard
- C: view the pieces at the ends of the chain
- V: view the entire domino chain
- D and G: indicate on which side to play when there is an ambiguity
- S: announce scores
- E: announce game information
- T: announce who is playing