Mao (also sometimes called Chairman, Dictator, Maul or Maui or, in Mongolia, Mangarti) is a card game that is popular among hackers. Since it is forbidden to say Mao's rules; new players are often told only "the only rule I can tell you is this one." As such, the rules of the game are discovered by playing or watching the game. A player that breaks a rule is penalized by being given an additional card from the deck. The person giving the penalty must state what the incorrect action was, but must not say the rule itself. As one might suspect, with a game of this nature, there are many variants of Mao in existence. While beginners sometimes complain that the dealer and other experienced players are simply making up possibly inconsistent rules (as in the game Mornington Crescent) the rules of Mao are consistent within each game and can be followed correctly.

Groups which frequently play together sometimes have universally accepted, differentiated sets of rules by which to play Mao. These can be stated at the beginning of the game, and in fact some groups have a rule that at the beginning of a game the dealer (or "dictator", or "Mao") must state the name of the variation he/she wants to play. An example of this would be that as Mao deals the cards, he/she says, "This is Four-Card Sour Cream Mao" in order to declare that a specific set of rules is in play for the game.

History
Mao is possibly descended from the German game Mau Mau, which has similar principles. Alternately, the name may be a reference to Mao Zedong; this theory proposes that the game of Mao is a parody of Communist China, where nobody purportedly knows the laws until they break them and are penalized. The idea of changing the rules without telling anyone is also part of this parody.

Mao began gaining popularity in the Universities of Cambridge and Oxford around 1975, though it was probably first invented some time before then. Mao is also popular at Center for Talented Youth camps. The Mao Page at John Macleod's card games site [1] also points out an interesting link to a passage from an Arthur Machen short story written in 1899.

Another, likely apocryphal, story is that Chairman Mao played this game with his prisoners, but instead of penalty cards, they lost a finger when violating the rules.

Other inductive games in which not all players know the rules include Eleusis, Penultima and Zendo; however, the secret rules in those games are made up at the start of play and disclosed at the end of each round, and the scope and subject matter of Eleusis, Penultima or Zendo rules may be more explicit and closely circumscribed. The game of Mao has a distinct aesthetic and sense of humor, so that some players consider it reminiscent of Calvinball, from the Calvin and Hobbes comic strip.

The game of Mao is alluded to in the title of The Mao Game, a 1997 novel written by (and a 1999 film directed by) Joshua Miller.


Regarding writing down the rules
Most Mao players feel that the enjoyment of players everywhere is enhanced both by the fact that the rules are not known in advance to new players, and by the growth and variety of differing versions through the oral and demonstrative tradition. Both of these are inhibited by the wide circulation of written sets of the rules. These players would argue that the rules should not be written down and disseminated publically. On the other hand, some Mao groups have used (or abused) the secrecy of the rules as a way to humiliate players unfamiliar with game, and these players may wish to disseminate what they've learned to prevent it from happening to others. Finally, a description of the rules may be used by an individual who is unfamiliar with Mao to start a game when no experienced players are available. Some people feel that while a description of the rules is inappropriate, describing an example game would be a reasonable compromise.

In any case there cannot be such a thing as an authoritative written description of the rules, so any descriptions or example games that are publically available may be inaccurate or suboptimal.





Rules of Mao
Ideally, a new player will learn the game from another the way it was meant to be learned. The following is intended for those who are interested in creating their own Mao variant or who are otherwise interested in the game without the desire to play it "as intended." 
Spoiler warning: Plot and/or ending details follow.

Public rules
The exact set of rules divulged to new players varies between groups of players: some groups will say only "the only rule I can tell you is this one", some groups reveal the goal of eliminating cards, and some groups might outline the "meta-rules". For instance:

'You may join or rejoin the game at any time by taking a place in the circle and drawing five cards. The object of the game is to eliminate all your cards. If someone catches you breaking a rule, they may give you a card from the draw pile with a statement of the offence. When you have eliminated all your cards, you say "Mao", which accrues you the right to introduce a new rule when you rejoin the game. You may introduce such a new rule by saying "new rule" and then enforcing infractions.' 

Variant rules
Once all players in a certain area know the ruleset, it may be interesting for them to abandon all 'normal' rules and have each player make up a rule of his own at the very beginning of the game. This variant is known as "Dutch Mao", or "The People's Democratic Dictatorship" [2] (and probably several other names). It has no restrictions on what cards to play (other than those made by the players) and can get very confusing, especially if multiple rules concerning turn order are in effect simultaneously.

In order to avoid interaction which would make the game unplayable, a variant called Cleopatran or Cleopatra's Mao has been developed. In this variant the game master makes up three rules (which he can set to interact in funny ways). Ideally, this does not upset the game balance, because once the game master fails to correct others breaking his rules, he is obliged to take two cards.

Another variant is Mini Mao [3], which starts with "no rules" (just turn-taking play-one-card-or-draw) and has a nominated player make up one secret rule, for the first round.


Rules of play
Mao is a card game of the Shedding family (also called the Stops family) in which the objective is to get rid of all of the cards in your hand. It is very similar to the card game UNO. Each player is dealt an initial hand with an equal number of cards; the exact number of cards dealt varies, but is generally either five or seven. The size of the deck also varies; it is good to have approximately one 52-card deck for every two or three players (or, in games with new players, one deck for every player), but missing or extra cards are not terribly important to gameplay. (Two decks combined is common; matching card backs aren't important, either.) Once the cards are dealt, the remaining cards are placed face down in a stack in the middle of the table, and the top card from the stack is turned over and placed next to it. In some variants, play commences with the player to the left of the dealer and proceeds clockwise; in others, the dealer chooses who begins and which direction it proceeds. Many variants penalize players for looking at their hands before the game begins or before the dealer looks at his or her hand.

A player may play any card in his hand which matches either the value or the suit of the card currently lying face-up on the table. The card played must be placed on top of this card, and the next player will have to play a card that matches the new one. If the player has no cards he can play, he must instead draw a new card from the top of the stack lying face-down and, in most variants, say something such as "Pass" or "Penalty Card". Usually, his turn is lost and he cannot play after he draws a card.


Further Rules
As noted above, each round, an additional rule is silently and secretly added to the game. There may also be additional rules that are already in effect at the beginning of the game, just to get things moving, and these rules may be known to all players, or perhaps only to the dealer. The rules will vary from group to group, and possibly from game to game, but most rules fall under one of the following four categories.

When <something> happens, perform an action (say a phrase, knock on the table, etc) 
When <something> happens, something about the game changes (skip the next person's turn, reverse turn order, anything can be played after a jack, etc) 
An action must always, or never, be performed (no unnecessary talking, don't straighten the pile, etc) 
Something fundamental about the game changes (a king is treated as if it were a jack for all game purposes) 
Note that the <something> listed above can be absolutely anything. Common examples include playing a specific card ("the ace of spade") or a specific type of card ("any red three"), but amongst sneakier players, the triggering conditions can become quite complicated. Such more complicated examples might include "when someone plays a face card on top of a non-face card", "when someone plays a nine with their right hand", or even "playing an odd numbered card on top of an even numbered card".


Examples
Here is a list of some specific examples of triggering conditions, actions, and game effects. To "create" a rule, one could pick a triggering condition, and then one or more action and/or game effect. The spirit of the rule is generally something in good fun, and may make more sense when in context; such as saying "He's dead, Jim" when playing what is known as "the suicide king".


Triggering Conditions

Playing a card of the same face value 
Playing additional cards of the same face value 
Playing a specific number of cards of the same face value 
Playing a card of a different-colored suit 
Playing an identical card (when multiple decks are used) 
Playing a specific card 
Straightening the pile of cards 
Switching from face cards to numbered cards 
Switching from numbered cards to face cards 
Playing a number card matching the number closest to the minute hand of the clock on the wall 
Playing a prime card, or a fibonacci card 
Playing a card 'upside down' (while many cards are vertically symmetrical, odd-numbered cards other than diamonds have a top and a bottom in most decks) 
Actions

Announce the name of the card being played 
Announce the suit only of the card being played 
Announce an incorrect name of the card being played (e.g., if the six of diamonds is played, the player must name any card other than the six of diamonds.) 
Snap your fingers 
Give the dealer (or perhaps the person to your left or right) a high five 
Say a particular phrase 
Say part of a particular well known phrase. Each time the condition is consecutively met, add more of the phrase. 
Slap or knock on the table. If the condition is met on the next player's turn, that player must slap or knock one more time than the previous player did 
Convey the idea of a particular location in interpretive dance 
Convey an idea via mime alone 
Say (or sing) "Jim Morrison is dead" the first time a particular condition is met, and then each subsequent time the condition is met, the player must call "X is dead", where X is a well-known dead person whose name has not previously been used in that session of play. Special penalties apply to any player who calls "Chairman Mao is dead." 
Name an animal (vegetable, city, ...) that hasn't been named before in the game 
Name a word with length equal to the number on the card played 
Name a word starting with the letter that the last named word ended with 
Begin a mini-game in which players must take turns recreating a dialogue from a well-known movie, TV episode, etc. The first player who fails to correctly continue the dialogue suffers a penalty. 
Game Effects

Skip the next player's turn (or next two players' turns, etc) 
Create an additional 'play' pile 
Name a player (other than yourself); that player skips their next turn 
Reverse the direction of play (e.g., if it was proceeding clockwise, it now goes counterclockwise) 
A player may lay as many twos (or another type of card) as he has in his hand in one turn 
A player must play a second valid card or draw a card, effectively taking a second turn in a row 
Give the next player one (or two) card(s) from the top of the deck. If the next player fufils the same condition that triggers this rule, the next player is given two (or four) cards, with each subsequent player upping the penalty for the next one. 
A rule is only applicable after a certain condition is fulfilled (either only immediately after, for the rest of the round, until another condition is fulfilled, or the rest of the game) 
The top card has a new value, and the next person who plays must play as if the card on top was that value 
Give a card to anyone who does not perform a particular action 
A particular card is now "wild" 
Cards played by a player out of turn, while still earning that player penalty cards, still perform the special effect other rules might have established 
In many variants, during the game, no speech is allowed other than that required by the rules. Some players feel that this rule reduces the amount of fun had while playing the game (especially for new players) and allow speech not required by the rules, as long as that speech does not conflict with any other rules in play.

Examples of particular speech rules include:

Point of Order. Any player (or only the dealer, in some variations) may at any time announce "point of order,", or in some variants "Put your cards down" at which point all players must put down their cards while discussion takes place. This time can be used to go to the bathroom, discuss a ruling, or to ask whose turn it really is. The point of order ends when the player that called point of order announces "end point of order," or "pick your cards up" at which point the cards are picked back up and play resumes. Players may not pick up their hands until the dealer picks up his own hand, or in some variations until the player who called point of order picks up his hand. This rule is often enforced by penalties such as "fondling the cards" or "premature peeking". Additionally, there may be a penalty for saying the word "Point of Order" during Point of Order; this may be circumvented by saying "Point of O", "P of Order", "P of O", and etc. In many variants, during a Point of Order, no players (including the dealer) are permitted to touch their cards at all.

Questions. In some variants, all players (sometimes including the dealer) are prohibited from asking questions. This rule is sometimes interpreted so as to prohibit formulating an utterance as a question, while permitting an utterance to be formulated as a statement that invites a response: for example, "What time is it?" would be prohibited, but, "I do not know what time it is, and I would like to know" would be permitted. In some variants, the prohibition on asking questions (and perhaps the prohibitions on swearing and blasphemy as well) are suspended during a Point of Order. Indeed, in these variations, questions can be observed to be the bane of the Point of Order's existence.

Swearing. Many variants prohibit swearing.

Blasphemy. Many variants prohibit blasphemy (including taking in vain the name of God, Jesus, Christ, or (in some variants), Chairman Mao.)

Last Card. Some variants require the player to announce "Last card" or in some cases "Mao" when he/she only has one card in his/her hand. In variants where a player who violates a speech rule is penalized repeatedly until he/she corrects the violation, the person would then be penalized again for "Lying" upon correcting his/her violation by calling "Last Card", since he/she would by that point have multiple cards due to the penalties.

Mao. Upon playing his/her last card, the player must call out "Mao" to win. If you forget to do this and also have the rule that you have to call "mao" on the last card, you have to call it twice. (once for no cards and once for the penalty that brings you up to one)

Required order of speech rules. In some variants, where multiple speech rules apply to a particular situation, the calls that the player is required to make must be made in the correct order. One typical order of operations is: calls resulting from the card's suit, then calls resulting from its rank, then calls resulting from the card's suit and rank simultaneously, and finally "last card" or "Mao" when applicable. For example, assume a variant where the "announce names of all played cards that are spades", "special 'have a nice day' rules for sevens", and "required call of 'thank you' upon playing a card with the same suit and rank as the top card". A seven of spades is the top card, and the player whose turn it is plays his last card, which is also a seven of spades. That player must call "Seven of spades, have a very nice day, thank you, Mao", in that order. Any variation is a penalizable offense (which would then bring the "Last card" rule back into play, etc.)

Cumulative effect of speech rules. In many variants, violations of speech rules are cumulative. Thus, if a player were to utter, "What the Hell?", this would constitute a violation of both the "Question" and the "Swearing" prohibitions, and the violator would be penalized for both.

In some variants, particular players are assigned particular titles, and particular rights or duties accrue to that player by virtue of that title. Examples: The dealer might have the title "Chairman Mao," "Mao Master," or "Game Master" and be the ultimate authority over whether a rule was broken. A player other than the dealer might have the title "Custodian of the Deck" and be the only player entitled to touch or handle cards during a Point of Order. (Typically, the Custodian of the Deck is charged with ensuring that piles of cards on the table are tidy.) A player other than the dealer might have the title "Minister of Foreign Affairs", and be the only player authorized to speak to people who are not playing the game.

There may be a time limit of approximately five seconds for each turn; if exceeded, the player gets a penalty card and either loses their turn or gets another penalty every five seconds thereafter.

Most times a penalty is called, one card is given to the offender. If the call was wrong, the caller of a penalty can be given the card back with a reason of "bad call". If the name of the game is mentioned at any time during play, the offender is penalized with at least two cards and sometimes a ridiculous number of cards, like thirty or fifty. Alternatively, this may only apply for the last card a player discard ("SFU variant": If they forgot to adhere to a certain rule, they will have to get penalty card for the mistake, plus "Lying", Cheating", "Stealing", "Taking the name of the great leader in vain". However, if Mao is just announced in the middle, it's just the last mentioned call.)

There are often many additional details and rules involved in a particular game of Mao, as the game lends itself quite readily to mutation. When playing multiple rounds of Mao, it is customary for a player (often the winner of the previous round, sometimes the next person to deal) to add one new rule to the game; after many rounds, many new rules will accumulate. Some players argue that having the player that won the previous round create new rules is unfair because that player will have an advantage in the next game and will be the most likely to win again, and suggest using a method which is fair to all players (such as simply rotating every deal). When playing with new players, some variants have a short period, generally 2 or 3 games, where no new rules are introduced to prevent the new players from being overwhelmed. Naturally, only the person who created the rule will initially know what it is. Some Mao players insist that 2 players know the new rule, so it can be consistently enforced. In that case, the winner tells the player with most (fewest?) cards about the new rule, or the dealer. Alternatively, player can tell people on what level they have (Base plus 2, for example, indicate two new rules in addition to the original base rules).

Keep in mind that these rules apply to only some variants; The game of Mao has mutated into a wide variety of possibilities, and each version will be unique in some ways and similar in others. In addition, newly introduced rules can totally change the nature of the game and can often take into account many unusual aspects - such as if a card is symmetrical or if it is a prime number. Like many role-playing games, the game will be much more fun if there are some experienced players present who have an appropriate attitude.

The rule-changing nature of Mao makes it a relative of Nomic, especially Imperial Nomic.