# Chan Instruction

Chan is a popular game in northern Vietnam using Vietnamese traditional To Tom cards. As a type of rummy game, players in the game take turn to meld cards into sets call Chan and Ca and discard trash until there is no trash left and the number of Chan is 6 or higher. With many combination of cards to earn points, it is often the case that players risk losing the game while aiming for big wins.

Once learning to recognize the cards, it is not hard to play the game. Mastering the game, however, requires a lot of practice.

Chan uses To Tom cards. There are 30 unique cards in a set, each has 4 cards.
Among the 30 cards, there are 3 cards in the rank *yeu*, called *lao, chi, thang* and the remaining 27 cards have a rank from 1 to 9 and one of 3 suits *vạn, văn, sách.* The ranks and suits are writen in *Nho*, a form of Chinese written language. The suit is written on the left
and the rank is written on the right.

Notice that a number of cards have a red stamp on it. These cards are called red card, and the remaining are called black cards.

Chan uses 100 out of 120 of the cards in the To Tom card set. Only cards in the rank from 2 to 9, and the card chi are used in the game.

Valid card combinations used in Chan are Chan and Ca. Chan is a pair of the same cards. Ca is a pair of cards with the same rank but different suits. The goal of the game is to meld cards and to discard trashes so that all cards in a hand are in various Chan and Ca.

In a Chan game, the first player has 20 cards, and all other players have 19 cards. The game begins with the first player discarding one card to his trash pile. The next person can either (1) meld the trash of the previous player or (2) hit a fresh card from the deck, then either meld or pass this card. If a card is melt by a player, he must (1) put down a card forming a Chan or Ca with the card he melds, and (2) put a card from his hand in his trash pile. If a player hits and passes a card, the card is simply throw in the trash pile of the player.

Each person takes turn to play with the exception of *chiu* when
a player plays out of order or *u`* when a player declares that he wins.

The following rules restricts which cards cannot be melt, which cards cannot be put down, and which card cannot be discarded. Essentially, they encourage taking Chan whenever possible though leaving enough flexibility if players do not wish to do so.

**Chan priority**: When you meld a card, if you can put down a Chan with that card, you must put down a Chan.**Cannot discard chan**: If you have a Chan on your hand, both cards in the Chan cannot be put down as trash or as part of a Ca.**Restriction for not taking in a Chan**: If you can meld a card to form a Chan while playing but decide not to do so, you cannot play that card as trash or as part of a Ca. If you have played a card as trash or as part of a Ca, you cannot later cannot meld the same card.**Cannot be selective when melding Ca**: If you have a Ca on your hand, you cannot meld and put down a Ca of the same rank.**Restriction when discard Ca**: If you have discarded both cards of a Ca, you cannot meld Ca in the future. If you have melt any Ca, you cannot discard both cards of a Ca in your hand.**Waiting for u`**: when you have only one card left and is waiting for u`, you are not allowed to meld Ca.

If someone has 3 identical cards, if the remaining card appears, either as
a discarded trash or a card hit from the deck, that person can *chiu*
to meld the card to obtain a set of 4 identical cards (which counts as 2 Chan),
even when it is not his turn. In the case he doesn't have the turn, he must
discard a card to replace the card being melt so that the game can continue
normally.

When a new card is hit from the remaining deck, if this card together
with the 19 cards of a player forms 10 Chan and Ca, with 6 or more Chan, that
player u` and wins the game. The player does not need to have the
current turn,
though the card has to be a new card, not a card someone discarded.
In the case the hit card is the *chi* card, the player must have
exactly 6 Chan and 4 Ca however.

An exception is made when the card is discarded and a player
*chiu* and has 10 Chan and Ca (with 6 or more Chan, and exactly 6 Chan
if the chiu card is a *chi* card). In that case, the person
*chiu u`* and wins the game.

The winning amount varies depending on many factors described bellow. Each
winning factor is associated with a point value and a partial value *dich*
used in the computation of the winning amount.

- U` thong: u` both previous game and this game, 3 points, 1 dich.
- U` chi`: the winner u` when having his turn, 3 points, 1 dich.
- Thien U`: the first player has 20 cards and they satisfy the u` condition, 3 points, 1 dich.
- Tom: the hand has 3 va.n, 3 va*n, 7 va*n, 4 points, 1 dich.
- Leo: the hand has 8 sach, 9 va.n, and chi card, 5 points, 2 dich.
- Bach Thu: winning with exactly 6 Chan, and there is no Ca of the same rank as the card used for u`, 4 points, 1 dich.
- Thien Khai: the hand initially contains 4 identical cards, 5 points 2 dich.
- Chiu: the final hand contains 4 identical cards, of which 3 were in the hand initially, 5 points 2 dich.
- Bon: The final hand contains 4 identical cards, of which 2 were in the hand initially, 5 points 2 dich.
- Bach dinh: all cards in the hand are black cards, 7 points, 4 dich.
- 8 red (8 do): the hand has 8 red card and 12 black cards, 8 points, 5 dich.
- Kinh tu chi: 4 chi cards and 16 black cards, 12 points, 9 dich.
- Thap thanh: u` with 10 Chan, 12 points 9 dich.

If the hand is *thap thanh*, the points won is the sum of all the point
values of applicable factors. Otherwise,
the points won is the point value of the
highest factor (break tie arbitrarily) plus the dich of all the remaining
factors.

Additional points, called ga` points, are also given for hands with bach dinh, 8 do, kinh tu chi, thap thanh, as well as for hands with a combination of bach thu and chi`.

You can click on an empty seat to participate in a game. Click on "Deal!" to start a game.

When you have 20 cards (after melding a card normally or after chiu), you can pick one card and click on "Discard" to discard it. When it is your turn, you can click on "Hit" to get a card from the remaining deck of card. To meld the card, you can click on either "Meld Chan", "Meld Ca", or "Meld Ca*". These 3 buttons mean the same thing, to meld the card. They are different to let you know that you are forming a Chan, a Ca, or in the last case, putting down a Chan even though you are having one more Ca in your hand if you meld.

The rules restricting your ability to meld and discard cards are enforced by the program. Unlike playing in real life, violation to the rules is not possible while playing.

While playing, the program always let you know the number of Chan and Ca you currently have. To quickly find all the cards that you can throw away without changing the number of Chan and Ca that you have, click on "Find Trash". Note that these cards may or may not be discarded, depending on your previous play.

When you need to pick a card that you can discard, clicking on "Quick Select" will select you one that you can surely discard. When you consider whether you meld a card or not, "Quick Select" will select all cards with the same rank as the card you are that card. A simple rule of thumb is that if the number of cards selected this way is odd, you can meld and discard trash. If the number of cards is even, you do not reduce trash but will have one more Chan and one less Ca after melding if such melding is allowed.

In an offline setting, players are free to decide whether chiu is good or not for their hands. At Vinagames, to reduce the waiting time after each card is discarded or hit, the server decides that automatically based on a set of internal rules. The rules should be reasonable in most of the situations. In particular, if the hand still has 3 or more trashes, chiu is done automatically to let players to discard trash. If you have only one card left and is waiting for u`, server most of the time skip chiu for you, and only do so if chiu will continue to let you wait for u`, possibly a different on, where your winning would increase if you indeed u`.

When the chiu card appears when you have your turn, you are free to decide whehter to chiu or not.