Rummy (Gin Rummy)

Overview

Gin Rummy is a two-player card game where players try to form sets and runs of cards to minimize the value of unmatched cards in their hand.

Status: 🔜 Coming Soon
Players: 2
Difficulty: Medium
Deck: 1 standard 52-card deck

Objective

Be the first to reach 100 points by forming melds (sets and runs) and minimizing deadwood (unmatched cards).

Rules

Card Values

Melds

Set: Three or four cards of the same rank

Run: Three or more consecutive cards of the same suit

Deadwood

Game Structure

  1. Deal: Each player receives 10 cards
  2. Draw: Take a card from stock or discard pile
  3. Discard: Discard one card to discard pile
  4. Knock: End round when deadwood is 10 or less
  5. Gin: End round with zero deadwood (bonus points)
  6. Undercut: Opponent has less deadwood than knocker

How to Play

Step 1: Deal

Step 2: Draw Phase

On your turn, you must draw one card from either:

Step 3: Meld Formation

Step 4: Discard Phase

Step 5: Knocking

When your deadwood is 10 or less, you can knock:

  1. Draw a card
  2. Arrange melds
  3. Discard one card face down
  4. Reveal your hand
  5. Opponent reveals their hand
  6. Opponent can “lay off” cards on your melds
  7. Calculate scores

Step 6: Going Gin

If you have zero deadwood:

  1. Declare “Gin!”
  2. Reveal your hand
  3. Opponent cannot lay off cards
  4. You get bonus points

Step 7: Scoring

If you knock:

If you go Gin:

Game ends when a player reaches 100 points

Strategy Tips

Early Game

  1. Draw from stock - Don’t reveal your strategy
  2. Keep flexible cards - Cards that can form multiple melds
  3. Watch discards - Remember what opponent discards
  4. Build runs - Easier to extend than sets

Mid Game

  1. Form melds quickly - Reduce deadwood
  2. Discard high cards - Minimize potential loss
  3. Track opponent’s picks - Guess their melds
  4. Keep low deadwood - Prepare to knock

Late Game

  1. Knock when safe - Don’t wait too long
  2. Go for Gin - If close to zero deadwood
  3. Defensive discards - Don’t help opponent
  4. Calculate odds - Know remaining cards

Advanced Tips

  1. Card counting - Track which cards have been played
  2. Baiting - Discard cards to mislead opponent
  3. Blocking - Hold cards opponent needs
  4. Timing - Know when to knock vs. go for Gin

Implementation Details

Planned Features

API Endpoints

GET https://deckofcardsapi.com/api/deck/new/shuffle/?deck_count=1
GET https://deckofcardsapi.com/api/deck/{deck_id}/draw/?count=10  # Deal to player 1
GET https://deckofcardsapi.com/api/deck/{deck_id}/draw/?count=10  # Deal to player 2
GET https://deckofcardsapi.com/api/deck/{deck_id}/draw/?count=1   # Start discard pile
GET https://deckofcardsapi.com/api/deck/{deck_id}/draw/?count=1   # Draw from stock

Technical Implementation

class RummyGame {
  final String deckId;
  final RummyPlayer player;
  final RummyPlayer opponent;
  final List<CardModel> discardPile;
  final int stockCount;
  final RummyGamePhase phase;
  final int playerScore;
  final int opponentScore;
}

class RummyPlayer {
  final List<CardModel> hand;
  final List<Meld> melds;
  final int deadwood;
  final bool hasKnocked;
  final bool hasGin;
}

class Meld {
  final MeldType type; // set or run
  final List<CardModel> cards;
}

enum MeldType { set, run }

Algorithms Needed

  1. Meld Detection: Find all valid sets and runs
  2. Optimal Melding: Minimize deadwood value
  3. Lay-off Detection: Find cards that fit opponent’s melds
  4. AI Strategy: Decision making for draw/discard/knock

Glossary

Scoring Examples

Example 1: Successful Knock

Your hand:

Opponent’s hand:

Score: 21 - 5 = 16 points for you

Example 2: Undercut

Your hand (knocked):

Opponent’s hand:

Score: 9 - 4 + 25 = 30 points for opponent (undercut bonus)

Example 3: Gin

Your hand:

Opponent’s hand:

Score: 18 + 25 = 43 points for you

References