Chaos;Jan has six different card types.
They are Action, Character, Hyper, Modifier, Negate, and Stock.
Each card type has specific timing rules for when they can be played.
A card's card type can be seen at the top of the card, next to its color.

• 1.1: Action cards are cards that cause a short-term effect and then is discarded. These cards can be played during any player's turn.
• 1.1a: When an Action card is put into play, its effect occurs and then is discarded.
• 1.1b: If an Action card is discarded or returned to a players hand from play before its effect occurs, its effect does not occur.
• 1.1c: Action cards can only be played when a player has priority. See the priority rule for more. Note that a player does not need to be the active player to play an Action card.
• 1.1d: After a player plays an Action card, they pass priority. This means that after a player plays an Action, another player may play a card before the first player can play another card.
• 1.1e: Some Action cards allow them to be played as a part of declaring riichi. This is a special case where the player does not need priority to play it.
• 1.1e.1: Playing an Action card this way creates a round of priority if the riichi is valid. Since the active player has played an Action card, they pass priority immediatly.
• 1.1e.2: This is usually phrased as, "Play only as you declare riichi." Playing the Action card is considered to be a part of declaring riichi in this case.
• 1.1f: Some Action cards have restrictions that limit when a player can play that card.

• 1.2: Character cards are cards chosen by each player before the game begins that determines that player's color and Hyper effect (see rule 1.3).
• 1.2a: Character cards are chosen before the first round.
• 1.2b: Character cards have a color indicated at the top, under the name.
• 1.2c: Character cards have a hyper effect. This is the effect that will occur when a player plays a Hyper card.
• 1.2d: Non-Hyper, non-Negate cards have bonus effects underneath their normal effects. This is marked with a symbol of the corresponding color followed by a colon.
• 1.2d.1: These symbols are 中, 發, and 白 for red, green, and white, respectively.
• 1.2d.2: This symbol means "If your Character has the same color as this card, you also get the following effect:"

• 1.3: Hyper cards are cards that have a powerful effect based on a player's Character card.
• 1.3a: The effect of a Hyper card is on the Character card of the player who played it.
• 1.3b: Some Hyper effects are also Stock effects. These effects follow the rules of Stock cards. See rule 1.6.
• 1.3c: Hyper cards can only be played when a player has priority, is the active player, and before that player draws a tile. See the priority rule.
• 1.3d: Some Hyper effects allow the player to play that Hyper when they are not the active player.
• 1.3d.1: If a Hyper effect allows the player to play it "at any time", that effect follows the rules of Action cards. See rule 1.1.
• 1.3e: Hyper cards cannot be negated.

• 1.4: Modifier cards are cards that alter the rules of the hand for each player.
• 1.4a: Modifier cards start in a separate deck called the "Modifier Deck".
• 1.4b: Players do not play Modifiers
• 1.4b.1: After a wind rotation or at the start of the game, a Modifier is drawn from the Modifier Deck and is put into play.
• 1.4b.2: Modifiers cannot be negated by players.
• 1.4c: A Modifier's effect lasts until it is replaced by another Modifier.
• 1.4c.1: Only one Modifier can be in play at a time.
• 1.4c.2: If a Modifier would be put into play, all Modifier cards in play are discarded, then that Modifier is put into play.
• 1.4d: A Modifier's color bonus effect applies to each player whose Character matches that color.
• 1.4e: If a Modifier's effect refers to "You", that effect applies to each player individually. Each player should treat that effect as though it were a Stock effect played by them.

• 1.5: Negate cards are cards that can prevent a card's effect from occuring.
• 1.5a: Negate cards use the sub-priority system.
• 1.5a.1: A Negate can only be played when a player has sub-priority. See rule 2.7.
• 1.5a.2: After a player plays a Negate card, they pass sub-priority.
• 1.5a.3: Negate cards can be played at the same time as another card.
• 1.5b: Each Negate card has the effect: "Negate the card played before this one."
• 1.5c: To negate a card means to have the player that played the negated card discard that card before any of its effect can occur.
• 1.5d: A Negate can be played in response to another Negate. When this happens, apply the effects in the reverse order they were played (most recent happens first). For example, East plays an Action, South plays a Negate, then East plays a Negate. East's Negate will discard South's Negate before it can discard the Action, letting the Action's effect apply normally.
• 1.5e: Negate effects know the player who played the card which it is attempting to negate. This is important for cards such as Bribery.

• 1.6: Stock cards are cards that have a lasting effect.
• 1.6a: Stock cards can only be played when a player has priority, is the active player, and before that player draws. See the priority rule.
• 1.6b: While a Stock effect is active, that card that caused that effect remains in play for as long as the effect is active.
• 1.6b.1: Once the effect is no longer active, the card that caused that effect is discarded.
• 1.6c: Most Stock effects have an "active time" phrase on them. For example, "Until the end of this hand," and, "The next time you deal in," are both active time phrases.
• 1.6c.1: Active time phrases dictate how long the Stock effect should remain active.
• 1.6c.2: If a Stock effect does not have an active time phrase, it remains active until the effect is no longer applicable. For example, Futuresight's effect can only apply up until a certain tile is discarded or until two of a certain tile are revealed from a hand. Once either of these conditions are met, Futuresight is discarded.
• 1.6c.3: If a Stock effect does not have an active time phrase, and its effect does not naturally end, its active time is until the end of the current hand.

• 2: Priority is the system that determines when a player can play a card. In short, players play cards in turn order, and each player gets a chance to play a card before any one player can play another card. Players may play Negate cards before another card's effect happens. If two players want to negate the same effect, the next player in turn order plays the Negate (playing a Negate after a Negate will discard the first Negate before it can discard the first card played).
• 2.1: At the beginning of the active player's turn (before they draw) and after that player draws a tile, that player receives priority.
• 2.2: While a player has priority, they may choose to either play a card or pass priority.
• 2.3: Priority is passed in turn order. For example, if East is the active player, they will pass priority to South, who will pass to West, et cetera.
• 2.4: When priority is passed, any card played whose effects have not yet occured applies their effects.
• 2.5: Priority is passed until each player has received priority but no cards were played since the last time they've received priority.
• 2.6: Once priority passing has stopped, no one has priority, and the next step in the Mahjong game may happen.
• 2.7: For Negate cards, there is another round of priority before main priority is passed. This is called "sub-priority".
• 2.7a: Sub-priority works identically to main priority.
• 2.7b: When a player plays a card, that player receives sub-priority.
• 2.7c: Once sub-priority passing has stopped, no one has sub-priority, and main priority is passed.
• 2.7d: If main priority tries to get passed before the round of sub-priority finishes, it waits for the round of sub-priority to finish first.

In Chaos;Jan, many effects ask the player to pay some amount of points.
Payments without a specified recipient go onto the table, such as a riichi payment.
Payments with a recipient go straight to that player's point total.
In general, a player cannot pay more points than they have.

• 3.1: Payments without a specified recipient go onto the table. For example, riichi payments.
• 3.1a: A general payment is a payment made without any player specified.
• 3.1b: Points paid through a general payment do not belong to any player.
• 3.1c: Points paid through a general payment are considered to be "on the table."
• 3.1d: Points on the table remain on the table as hands change and winds rotate.
• 3.1e: Whenever a player wins a hand, they receive all the points on the table.
• 3.1f: Some card effects allow you to take points on the table.
• 3.1f.1: Cards should specify the amount of points that can be taken from the table
• 3.1f.2: The table must have at least the specified amount of points in order for the player to take them. If it does not, the instruction is ignored.
• 3.1f.3: If the card effect says "up to" in its specification, the player can still take points from the table even if there is not enough points on the table. For example, Riichi Robbery's effect.
• 3.1f.4: If the card effect says "any number" in its specification, the player chooses the number of points to take.
• 3.1f.5: Points can only be taken or paid in the denominations of the point sticks, those being: 100, 500, 1000, 5000, and 10000. See the equipment rule. (Note: rule does not exist at time of writing)
• 3.1g: Players cannot pay more points than they have in their point total.

• 3.2: Payments with a specified recipient go straight to that player's point total. For example, ron payments.
• 3.2a: A specified payment is a payment made with a player specified.
• 3.2b: Points paid through a specified payment always belong to a player; they are never on the table.
• 3.2c: Whenever a player wins a hand, there is a specified payment. See rule ___ (rule does not exist at time of writing: will later be rules on ron and tsumo payments).
• 3.2c.1: This specified payment is called the point exchange.
• 3.2c.2: Some card effects may double the point exchange. This means that the value being paid is twice that what it would be normally.
• 3.2c.2a: This does not care who is paying who. This is important for Wandering Wareme's effect.
• 3.2c.3: A player may pay point exchange costs even if that player does not have enough points to actually pay the cost. If a player does pay more points than they have, their point total will be negative. This is an exception to rule 3.1g.

• 4: Players begin the game with 5 cards in their hand. They draw a new card at the beginning of each hand, and if they lost points due to a point exchange, they draw an additional card. Some card effects may also allow players to draw cards.
• 4.1: Players begin the game with 5 cards from the Action Deck in their hand. See rule 5.1d.
• 4.2: At the beginning of each hand, each player draws a card from the Action Deck.
• 4.3: At the beginning of each hand, if a player paid a point exchange last hand, that player draws a card from the Action Deck. See rule 3.2c.
• 4.4: Some card effects allow players to draw cards outside of the normal times. When a card asks a player to draw a number of cards, they draw that many cards from the Action Deck.
• 4.5: Players cannot draw from the Modifier Deck.

There are two different decks in Chaos;Jan: The Action Deck and the Modifier Deck.
The Modifier Deck holds all of the Modifier cards, and the Action deck holds all the other cards (except Character).
See rules section 1 for the different card types.

• 5.1:The Action Deck contains all non-Character, non-Modifier cards, and is the deck that players draw from.
• 5.1a: The Action Deck is the deck which players draw cards from. See rule 4.
• 5.1b: The card types in the Action deck are: Action, Hyper, Negate, and Stock.
• 5.1c: The Action Deck is a shared deck. All players draw from the same deck.
• 5.1d: The Action Deck is built before the game begins.
• 5.1d.1: While building the Action Deck, it should contain at least two Hyper cards for each player (i.e. eight for a 4-player game; six for a 3-player game), and at least 10 Negate cards. Players may agree to play with a different number of Hyper and Negate cards.
• 5.1d.2: Players should choose three different Action cards and three different Stock cards to be shuffled into the deck.
• 5.1d.3: Any one player cannot choose two or more copies of the same Action or Stock card to be shuffled into the deck. Two different players bringing the same card is allowed.

• 5.2: The Modifier Deck contains all Modifier cards and is the deck where new Modifiers enter play from.
• 5.2a: When a new Modifier is to be put into play, it is drawn from the Modifier Deck. See rule 1.4b.
• 5.2b: The only card type in the Modifier Deck is Modifier.
• 5.2c: The Modifier Deck is a shared deck.
• 5.2d: The Modifier Deck is built before the game begins.
• 5.2d.1: Players should choose three different Modifier cards to be shuffled into the deck.
• 5.2d.2: The Modifier Deck cannot contain two or more copies of the same Modifier. Each card must be unique.