Gin rummy

Variant played: Two players · knock instead of draw in this variant · limit 10 · Version 1.0.0

Objective

Build melds and reduce the value of unmatched cards, called deadwood.

Setup

1. 2 players, 10 cards each; one face-up card starts the discard pile.
2. Combination: a group of 3 or 4 cards of the same rank, or a run of at least 3 consecutive cards of the same suit.
3. Low aces only; Q-K-A is not allowed.
4. Deadwood value: Ace 1, 2-10 face value, face cards 10.

Turn or round flow

1. On your turn, draw the top card from the stock or discard pile.
2. Then discard one card; you cannot take back the discard and immediately reject that same card.
3. After discarding, the player may knock if their deadwood is 10 or less, or declare gin at 0.

Legal actions and obligations

• A card can belong to only one combination in the optimal calculation.
• After a non-gin knock, the opponent may lay their deadwood cards onto the knocker's melds.
• No layoff is allowed against a gin.

Score

• Knock successful: difference between opponent deadwood after layoff and knocker deadwood.
• Undercut: if the opponent has deadwood less than or equal to yours, they score the difference +25.
• Gin: 25 + the opponent's total deadwood points.
• A dead hand after the stock is exhausted scores no points.

End of game

• The round ends by knock/gin or when the stock has only two cards left without a knock.
• The game ends when a player reaches 100 points; configurable game bonuses are off by default.

Locked special cases and variants

• On the first turn, the non-dealer may take the upcard or pass; the dealer then has the same option; if both pass, the non-dealer draws from the stock.
• Big Gin and Oklahoma Gin are disabled.

Artificial intelligence

The AI uses only its hand, public cards, the allowed history, and the legal actions sent by the server.

• Easy keeps completed melds and discards the highest deadwood.
• Normal calculates the best meld layout and avoids discarding cards that help the opponent, based on visible history.
• Hard estimates the opponent's likely cards, compares an immediate knock with going for gin.