Gin Rummy is one of the most popular forms of rummy. The game is generally played by two players, each receiving ten cards.

One standard deck of 52 cards is used. Cards in each suit rank, from low to high:
Ace 2 3 4 5 6 7 8 9 10 Jack Queen King. The cards have the following values

Face cards (K,Q,J)	10 points
Ace	1 point
2 through 9	2 through 9 points(card value)

The first dealer is chosen randomly by drawing cards from the shuffled deck - the player who draws the lower card deals. Subsequently, the dealer is the loser of the previous hand. In a serious game, both players should shuffle, the non-dealer shuffling last, and the non-dealer must then cut.

Each player is dealt ten cards, one at a time. The twenty-first card is turned face up to start the discard pile and the remainder of the deck is placed face down beside it to form the stock. The players look at and sort their cards.

The object of the game is to collect a hand where most or all of the cards can be combined into sets and runs and the point value of the remaining unmatched cards is low.

• A run, or sequence, consists of three or more cards of the same suit in consecutive order, such as 4,5,6 of clubs or 8,9,10 of hearts.
• A set, or group, is three or four cards of the same rank, such as 7 of diamonds, hearts and spades.
• A card can belong to only one combination at a time - you cannot use the same card as part of both a set of equal cards and a sequence of consecutive cards at the same time. For instance if you have a set of three 7's (Hearts, Diamonds, Spades), you cannot also use the 7 of Hearts as part of a run of 7, 8, 9 of Hearts.
• Note that in Gin Rummy the Ace is always low. A-2-3 is a valid sequence but A-K-Q is not.

A normal turn consists of two parts:

A Player can end the play at their turn if, after drawing a card, they can form sufficient sets and runs of their cards into valid combinations.

• This is done by discarding one card face down on the discard pile and exposing their whole hand, arranging it as far as possible into sets (groups of equal cards) and runs (sequences).
• Any remaining cards from their hand which are not part of a valid combination are called unmatched cards or deadwood. and the total value of the deadwood must be 10 points or less.
• Ending the play in this way is known as knocking, presumably because it used to be signalled by the player knocking on the table, though nowadays it is usual just to discard face down.
• Gin is knocking with no unmatched cards at all, and earns a special bonus. (Note. Although most hands that go gin have three combinations of 4, 3 and 3 cards, it is possible and perfectly legal to go gin with two 5-card sequences.)
• A player who can meet the requirement of not more than 10 deadwood can knock on any turn, including the first. A player is never forced to knock if able to, but may choose instead to carry on playing, to try to get a better score.
• The opponent of the player who knocked must spread their cards face-up, arranging them into sets and runs where possible. Provided that the knocker did not go gin, the opponent is also allowed to lay off any unmatched cards by using them to extend the sets and runs laid down by the knocker - by adding a fourth card of the same rank to a group of three, or further consecutive cards of the same suit to either end of a sequence. (Note. Cards cannot be laid off on deadwood. For example if the knocker has a pair of twos as deadwood and the opponent has a third two, this cannot be laid off on the twos to make a set.)
• If a player goes gin, the opponent is not allowed to lay off any cards.
• Note that the knocker is never allowed to lay off cards on the opponent's sets or runs.

The play also ends if the stock pile is reduced to two cards, and the player who took the third last card discards without knocking. In this case the hand is cancelled, there is no score, and the same dealer deals again. Some play that after the player who took the third last stock card discards, the other player can take this discard for the purpose of going gin or knocking after discarding a different card, but if the other player does neither of these the hand is cancelled.

• Each player counts the total value of their unmatched cards. If the knocker's count is lower, the knocker scores the difference between the two counts.
• If the knocker did not go gin, and the counts are equal, or the knocker's count is greater than that of the opponent, the knocker has been undercut. In this case the knocker's opponent scores the difference between the counts plus a 10 point bonus.
• GIN - A player who goes gin scores a bonus 20 points, plus the opponent's count in unmatched cards, if any. A player who goes gin can never be undercut. Even if the other player has no unmatched cards at all, the person going gin gets the 20 point bonus the other player scores nothing.

• For all variations or normal play, the original Up Card is always displayed
• Point or Scoring Variations
  • Points for Gin (10,15,20,25)
  • Bonus points for Undercut (10,15,20,25)
  • Score to end game (100, 150, 200)
• Allowed Methods to end hand
  • Gin Only
  • Knocking (not Gin) allowed
  • Oklahoma Variation - if an ace is turned up for the original Up Card, you may only go gin.
  • Red/Black Variation - The initial upcard determines if gin and knocking, or gin only is required. Red upcard determines player can only go out with gin, black upcard allows either.
• Allowed Deadwood
  • 10
  • 15
  • 20
  • Oklahoma Variation - The value of the original face up card determines the maximum count of unmatched cards with which it is possible to knock. Face Cards denote 10 as usual. So if a seven is turned up, in order to knock you must reduce your count to 7 or fewer.
• Timer - To be implemented.
• Teams - ability for members of the team as kibbitzers to swap out with the seated player when they lose.