Demo Game Server

A slot machine game server that provides betting functionality with configurable symbol weights and outcome probabilities.

API Documentation

Base URL

http://localhost:3000/api

Endpoints

Place a Bet

POST /bet/place

Places a single bet and returns the result.

Request Body:

{
  "amount": number,           // Required: Bet amount (must be one of: 1, 5, 10, 25, 50, 100)
  "autowin": boolean,        // Optional: Force a win (three of a kind)
  "autolose": boolean,       // Optional: Force a loss (no win)
  "outcomeWeights": {        // Optional: Customize win type probabilities
    "threeOfAKind": number,  // Weight for three of a kind (must be positive, typically 0-1)
    "twoOfAKind": number,    // Weight for two of a kind (must be positive, typically 0-1)
    "noWin": number         // Weight for no win (must be positive, typically 0-1)
  },
  "symbolWeights": {         // Optional: Customize symbol probabilities
    "0": number,            // Weight for 🍒 (must be positive, typically 0-1)
    "1": number,            // Weight for 🍊 (must be positive, typically 0-1)
    "2": number,            // Weight for 🍋 (must be positive, typically 0-1)
    "3": number,            // Weight for 🍇 (must be positive, typically 0-1)
    "4": number,            // Weight for 7️⃣ (must be positive, typically 0-1)
    "5": number             // Weight for 💎 (must be positive, typically 0-1)
  }
}

Response:

{
  "symbols": number[],      // Array of 3 symbol indices
  "betAmount": number,      // Amount bet
  "winAmount": number,      // Amount won (0 if no win)
  "isWin": boolean,         // Whether the bet was a win
  "winType": string         // "THREE_OF_A_KIND", "TWO_OF_A_KIND", or "NO_WIN"
}

Error Responses:

• 400 Bad Request: Invalid bet amount or weights
• 500 Internal Server Error: Server error

Run Many Spins

POST /bet/many-spins

Runs multiple spins and returns statistics.

Request Body:

{
  "amount": number,           // Required: Bet amount (must be one of: 1, 5, 10, 25, 50, 100)
  "spins": number,           // Optional: Number of spins (default: 1000, max: 10000000)
  "autowin": boolean,        // Optional: Force all wins
  "autolose": boolean,       // Optional: Force all losses
  "outcomeWeights": {        // Optional: Customize win type probabilities
    "threeOfAKind": number,  // Weight for three of a kind (must be positive, typically 0-1)
    "twoOfAKind": number,    // Weight for two of a kind (must be positive, typically 0-1)
    "noWin": number         // Weight for no win (must be positive, typically 0-1)
  },
  "symbolWeights": {         // Optional: Customize symbol probabilities
    "0": number,            // Weight for 🍒 (must be positive, typically 0-1)
    "1": number,            // Weight for 🍊 (must be positive, typically 0-1)
    "2": number,            // Weight for 🍋 (must be positive, typically 0-1)
    "3": number,            // Weight for 🍇 (must be positive, typically 0-1)
    "4": number,            // Weight for 7️⃣ (must be positive, typically 0-1)
    "5": number             // Weight for 💎 (must be positive, typically 0-1)
  }
}

Response:

{
  "totalSpins": number,     // Total number of spins
  "totalWinAmount": number, // Total amount won
  "totalBetAmount": number, // Total amount bet
  "expectation": number,    // Expected value per spin
  "winRate": number,        // Win rate as a percentage
  "returnToPlayer": number, // Return to player as a percentage
  "standardDeviation": number // Standard deviation of win amounts
}

Error Responses:

• 400 Bad Request: Invalid bet amount, number of spins, or weights
• 500 Internal Server Error: Server error

Symbol Values

The slot machine uses the following symbols with their respective values:

• 🍒 (Cherry): 2x
• 🍊 (Orange): 3x
• 🍋 (Lemon): 4x
• 🍇 (Grapes): 5x
• 7️⃣ (Seven): 10x
• 💎 (Diamond): 20x

Win Types and Payouts

• Three of a Kind: All three symbols match
  • Payout: bet amount × symbol value
• Two of a Kind: Two symbols match
  • Payout: bet amount × symbol value × 0.2
• No Win: All symbols are different
  • Payout: 0

Weight System

The game uses a weight system to control probabilities:

1. Outcome Weights: Control the probability of different win types

   • Each weight must be a positive number
   • Weights are typically kept between 0 and 1
   • Higher weights increase the probability of that outcome
   • Weights are relative to each other

2. Symbol Weights: Control the probability of each symbol appearing

   • Each weight must be a positive number
   • Weights are typically kept between 0 and 1
   • Higher weights increase the probability of that symbol
   • Weights are relative to each other

Example Requests

Place a Bet with Custom Weights

{
  "amount": 10,
  "outcomeWeights": {
    "threeOfAKind": 0.1,
    "twoOfAKind": 0.3,
    "noWin": 0.6
  },
  "symbolWeights": {
    "0": 0.2, // 🍒
    "1": 0.2, // 🍊
    "2": 0.2, // 🍋
    "3": 0.2, // 🍇
    "4": 0.1, // 7️⃣
    "5": 0.1 // 💎
  }
}

Run Many Spins with Default Settings

{
  "amount": 5,
  "spins": 1000
}

Development

Prerequisites

• Node.js 18.x
• npm

Installation

npm install

Running Tests

npm test

Development Mode

npm run dev

Building

npm run build

Production

npm start