Gin Rummy is a two-player Rummy variant where you knock when your deadwood is low. The goal is to meld all your cards or go out with minimal deadwood.
Deal 10 cards each. Turn one card up to start the discard pile; the rest is the stock.
Draw from stock or discard, then discard one card. Form sets and runs. You may knock when your deadwood (unmelded cards) totals 10 or fewer.
If you meld all 10 cards with no deadwood, you "go gin" for a 25-point bonus. The opponent cannot undercut a gin.
After a knock, both reveal. If the knocker's deadwood is lower, they score the difference; if the opponent's is lower or equal, the opponent "undercuts" for 25 plus the difference. First to 100 wins.
Ending the hand by revealing your cards when your unmelded deadwood is 10 points or fewer.
When the non-knocker has equal or lower deadwood, they steal the hand and score a 25-point bonus.
Gin is two-player, you cannot lay off onto opponent melds, and you can win by knocking with low deadwood rather than going fully out.