Overview

A multiplayer game server for the Countdown word and numbers game, based on the popular British television show. The server manages real-time gameplay between two players, handling both the letters round (word formation) and numbers round (arithmetic calculations).

Key Features

🎮 Game Mechanics

• Letters Round: Players form the longest possible word from 9 random letters
• Numbers Round: Players use 6 numbers and basic arithmetic to reach a target
• Real-time Gameplay: Live synchronization between connected players
• Scoring System: Automated scoring based on official Countdown rules

🔗 Multiplayer Support

• Room Management: Create and join game rooms
• Player Matching: Automatic or custom player pairing
• Turn-based Logic: Enforced game flow and timing
• Spectator Mode: Watch ongoing games

⚡ Real-time Communication

• WebSocket Integration: Live updates during gameplay
• Game State Synchronization: Consistent state across all clients
• Chat System: In-game communication between players
• Reconnection Handling: Resume games after disconnection

Technical Implementation

Backend Architecture

Built with Spring Boot and Java:

• Spring WebSocket: Real-time bidirectional communication
• Game State Management: Thread-safe game logic handling
• Room Service: Player matchmaking and room lifecycle
• Dictionary API: Word validation for letters rounds

Game Logic

Core Countdown mechanics:

• Letter Generator: Random vowel/consonant selection
• Number Generator: Target numbers and calculation sets
• Word Validator: Dictionary lookup and scoring
• Math Solver: Verify arithmetic solutions

Data Management

Efficient game data handling:

• In-Memory Storage: Fast access to active game states
• Session Management: Player connection tracking
• Game History: Optional persistent storage for completed games

Game Flow

Starting a Game

1. Room Creation: Player creates or joins a game room
2. Player Matching: Wait for second player or invite friend
3. Game Initialization: Server generates letters/numbers for rounds

Letters Round

1. Letter Selection: 9 letters (mix of vowels/consonants)
2. 30-Second Timer: Players form words simultaneously
3. Word Submission: Players submit their best word
4. Validation & Scoring: Dictionary check and point calculation

Numbers Round

1. Number Generation: 6 numbers + target (100-999)
2. 30-Second Timer: Players calculate using basic arithmetic
3. Solution Submission: Submit calculation steps
4. Verification: Server validates mathematical accuracy

API Endpoints

Game Management

• POST /games/create - Create new game room
• POST /games/{roomId}/join - Join existing room
• GET /games/{roomId}/status - Get current game state

Gameplay

• POST /games/{roomId}/submit-word - Submit word for letters round
• POST /games/{roomId}/submit-calculation - Submit numbers solution
• GET /games/{roomId}/results - Get round results

WebSocket Events

• game.started - Game initialization
• round.letters - New letters round
• round.numbers - New numbers round
• player.submitted - Player submission
• round.results - Round scoring results

Getting Started

# Clone the repository
git clone https://github.com/ljubinkovicdj93/countdown-server.git
cd countdown-server

# Build and run
./mvnw spring-boot:run

# The server will start on http://localhost:8080

Configuration

# WebSocket configuration
websocket.allowed-origins=*
websocket.endpoint=/countdown

# Game settings
game.letters-time-limit=30000
game.numbers-time-limit=30000
game.dictionary-api=https://api.dictionaryapi.dev

Future Enhancements

• Tournament Mode: Multi-round competitions
• Player Rankings: ELO-based rating system
• Custom Dictionaries: Language-specific word lists
• Replay System: Watch completed games
• Mobile Client: Companion mobile app

This project demonstrates real-time game development, WebSocket communication, and implementing complex game logic with Java and Spring Boot.