Oklahoma Gin is a gin rummy variant which is a skill-based card game for 2 to 4 players. The game is played with one standard deck of 52 cards. In a two player game each player is dealt 10 cards. In a 3 to 4 player game each player is dealt 7 cards.

The goal in Oklahoma Gin is to be the first player to get rid of all the cards in your hand by melding them into sets and runs and by laying them down. A "set" contains 3 to 4 cards of the same value while a "run" consists of 3 or more consecutive cards of the same suit.

The players must begin a turn by drawing a card either from the stick or discard piles and adding it to their hand. To complete their turn players must discard a single card from their hand onto the discard pile.

There are three ways to win a round of Oklahoma Gin. Gin, knock and undercut. Gin is when players meld all the cards in their hand laying them down on the table at once and discarding their last card while having no deadwood (unmatching cards) left. Knock is when players meld all the cards in their hand and their deadwood count is equal to the opening card's face value or lower. Undercut is when a players deadwood count is equal to the Knocker's or lower.

After players Gin, their opponents may lay their melds down onto the table to decrease their deadwood count and therefore reduce their amount of penalty points. After players Knock defeated opponents may lay their melds down onto the table and add matching cards to the Knocker's original melds only. Therefore the knock move provides the defeated players with an opportunity to reduce their amount of penalty points far more than Gin.

The winners of multi-round Oklahoma Gin games are the players to accumulate the highest amount of points. Gin is the move that rewards the winner with the highest amount of points. Players who Gin are rewarded with 25 points while their defeated opponents receive double the amount of their deadwood count as penalty points. Undercut rewards the winners with 20 points and their defeated opponents receive the difference in the counts of the winner's deadwood and their own as penalty points. The last winning move is Knock. This move rewards the Knocker with 10 points, and his defeated opponents are all credited with their deadwood count minus the Knocker's deadwood count as penalty points.

In Oklahoma Gin, Aces count as 1 point and all the face cards are worth 10 points, while all other cards are worth their face value.