System Requirements Document (SRD) for sunny-subway

1. Introduction

The sunny-subway project aims to create a unique and powerful endless runner game that serves as an alternative to the popular Subway Surfer. This game will focus on delivering a fresh and captivating experience with innovative gameplay mechanics, visually stunning aesthetics, and a thrilling pace. Designed for a global audience, the game will be tailored to the Australian market with locale-specific elements such as time zones (AEST) and cultural references.

2. System Overview

sunny-subway will be an endless runner game where players navigate through dynamic environments, avoiding obstacles, collecting power-ups, and achieving high scores. The game will differentiate itself with a unique theme, powerful gameplay mechanics, and visually immersive elements. It will feature a variety of characters, customizable elements, and a progression system to keep players engaged.

The game will be available on both mobile platforms (iOS and Android) and web browsers, ensuring accessibility for a wide audience. The backend will support real-time leaderboards, user profiles, and cloud saves.

3. Functional Requirements

• As a Player, I should be able to select from a variety of characters with unique abilities.
• As a Player, I should be able to navigate through dynamically changing environments.
• As a Player, I should be able to collect power-ups that enhance gameplay.
• As a Player, I should be able to unlock achievements and rewards.
• As a Player, I should be able to customize my character's appearance.
• As a Player, I should be able to compete on global leaderboards.
• As a Player, I should be able to save my progress across devices.
• As a Player, I should experience a thrilling pace with increasing difficulty levels.
• As a Developer, I should be able to add new characters, environments, and power-ups seamlessly.

4. User Personas

1. Player

• Description: Casual and competitive gamers who enjoy endless runner games.
• Goals: Achieve high scores, unlock rewards, and enjoy a visually immersive experience.
• Pain Points: Repetitive gameplay, lack of customization, and poor performance on older devices.

2. Developer

• Description: Game developers responsible for maintaining and updating the game.
• Goals: Easily add new content, fix bugs, and ensure smooth performance.
• Pain Points: Complex codebase, lack of modularity, and difficulty in deploying updates.

5. Visuals Colors and Theme

The visual theme for sunny-subway will be vibrant and dynamic, with a focus on creating an immersive and energetic atmosphere. The color palette will include:

• Primary Colors: Bright yellow (#FFD700), electric blue (#1E90FF), and vivid orange (#FF4500).
• Secondary Colors: Deep purple (#800080), lime green (#32CD32), and crisp white (#FFFFFF).
• Backgrounds: Gradient skies transitioning from sunrise to sunset, with dynamic lighting effects.

The environments will feature a mix of urban and natural settings, such as futuristic cities, lush forests, and sandy beaches, reflecting the Australian landscape.

6. Signature Design Concept

Interactive Solar-Powered Subway Tracks

The home screen of sunny-subway will be a visually stunning, interactive solar-powered subway track. The track will glow and pulse with energy as the player interacts with it.

Key Features:

• Dynamic Lighting: The track will shift colors based on the time of day (e.g., warm hues at sunrise, cool tones at night).
• Interactive Animations: As players swipe or tap, the track will ripple and react, creating a sense of energy and motion.
• 3D Perspective: The camera will subtly tilt and zoom as players navigate the menu, giving a sense of depth and immersion.
• Character Showcase: Selected characters will perform idle animations on the track, showcasing their unique abilities.
• Ambient Soundscape: A mix of futuristic subway sounds and uplifting music will play in the background, enhancing the atmosphere.

This design will make the game instantly memorable and set the tone for the high-energy gameplay.

7. Non-Functional Requirements

• The game must maintain a consistent frame rate of 60 FPS on modern devices.
• The game must load within 5 seconds on mobile devices.
• The game must support offline play with cloud sync for progress when reconnected.
• The game must be optimized for both iOS and Android platforms.
• The game must support localization for multiple languages, starting with English (AU).

8. Tech Stack

Frontend

• React Native for mobile app development.

Backend

• Python with FastAPI for server-side logic.

Database

• MySQL for structured data storage, using Alembic for migrations.

AI Models

• GPT 5.2 for generating user-friendly responses in tutorials and help sections.
• Google Nano Banana for generating dynamic in-game visuals.

AI Tools

• Langchain for integrating AI-driven features.
• Litellm for LLM routing.

Orchestration

• Docker and docker-compose for local development.
• Kubernetes for server-side orchestration.

9. Assumptions and Constraints

• The game will primarily target mobile platforms but will also support web browsers.
• The initial release will focus on the Australian market, with plans for global expansion.
• The game must comply with app store guidelines for both iOS and Android.
• The game will require periodic updates to introduce new content and features.

10. Glossary

• Endless Runner: A game genre where the player character is in constant motion, and the objective is to avoid obstacles and achieve the highest score possible.
• Power-Up: An item that temporarily enhances the player's abilities.
• Cloud Sync: A feature that allows game progress to be saved and accessed across multiple devices.
• Localization: Adapting the game for different languages and regions.