How to Play Gin Rummy
On each round a player either:
(1) Draws top card of the discard pile, or 1 card from the stock pile
(2) "Knocks", thus ending the round, (but only if certain conditions are met)
(3) Throws away one card onto the discard pile
Play goes back and forth until one player knocks or only 2 cards are left in the stock pile. In this case, it´s a draw.
Knocking in Gin Rummy
You may not knock unless you have a score of 10 or less in your deadwood. It is compulsary to knock if you have a score 0 in your deadwood (this is going Gin or having a Gin hand).
To knock, discard your card into the discard pile as you would normally do, and declare that you are knocking by placing your discard face down. Then lay out your hand with the melds clearly shown and all the deadwood set to one side for easy counting. The other player may then discard any deadwood cards that fit into your melds.
Say the knocking player has a meld of 3 eights. The other player has an eight in his or her deadwood. He can discard that King, bringing his deadwood count down by 8.
If the knocking player has Gin Hand, the other player is not permitted to discard any cards.
Gin Rummy Scoring
You score pointsi n Gin Rummy as follows:
Knock Points - after a player knocks, and the lay offs are finished, the knocking player gets a score equal to the difference between the two hands. So say a player knocks with 7, and the defender has 11 deadwood pointsleft after laying off, the knocking player is awarded 3 points.
Gin: - after going Gin, you´ll get a bonus of 25 points PLUS the sum of the deadwood in their opponent's hand. Your opposite number cannot lay off if you go Gin.
Under Cut - (or under knocking). This happens when you knock too early and your opposite number has a deadwood count less than or equal to your card count. In this scenario, the defender gets an undercut bonus of 25 points plus the difference between the two hands.
Game Bonus - once a player has 100 points (or some other prearranged target) the match finishes, and that player gets an additional Game Bonus of 100 points.
Line Bonus - (or box bonus). This is added at the end of the Gin Rummy match. 25 points is added to every hand played.
Big Gin - before knocking, if all 11 cards in your hand make up a legal gin, you can keep the extra card as part of the hand, and you get an additional six points: the so called "Big Gin" bonus.
Shut out Bonus - if a match finishes with the winner having won each and every hand, the points for each hand are multiplied by two before the Line Bonus gets tacked on.