NFR Requirements - Nokia Snake Game

Overview

Unit Name: Nokia Snake Game (Monolithic)
Type: Single monolithic web application
Deployment: Web-based, fully offline capable
Target Audience: General users on desktop and mobile devices

Performance Requirements

Frame Rate and Responsiveness

Requirement: NFR-PERF-001
Category: Performance
Priority: High
Description: Game must maintain minimum 30 FPS on low-end devices

Specifications:

• Target Frame Rate: 30 FPS minimum, 60 FPS preferred
• Input Latency: < 50ms from keypress to game state update
• Rendering Latency: < 33ms per frame (30 FPS)
• Device Support: Low-end devices (2GB RAM, integrated graphics)

Acceptance Criteria:

• Game maintains 30+ FPS on devices with 2GB RAM
• Input response feels immediate (< 50ms latency)
• No frame drops during normal gameplay
• Smooth animations and transitions

Testing Approach:

• Manual testing on low-end devices
• Performance profiling with browser DevTools
• Frame rate monitoring during gameplay

Load Time Performance

Requirement: NFR-PERF-002
Category: Performance
Priority: Medium
Description: Fast initial load and game start times

Specifications:

• Initial Load: < 3 seconds on 3G connection
• Game Start: < 500ms from menu to gameplay
• Asset Loading: Progressive loading, non-blocking
• Bundle Size: < 500KB total (minified + gzipped)

Acceptance Criteria:

• Page loads in < 3 seconds on 3G
• Game starts immediately when user clicks "Start"
• No loading screens during gameplay
• Minimal bundle size through code splitting

Memory Management

Requirement: NFR-PERF-003
Category: Performance
Priority: Medium
Description: Efficient memory usage and garbage collection

Specifications:

• Memory Footprint: < 50MB during gameplay
• Garbage Collection: Minimal GC pauses (< 10ms)
• Object Pooling: Reuse game objects where possible
• Memory Leaks: Zero memory leaks over extended play

Acceptance Criteria:

• Memory usage stays under 50MB
• No noticeable GC pauses during gameplay
• Memory usage stable over 1+ hour sessions
• No memory leaks detected in profiling

Browser Compatibility Requirements

Supported Browsers

Requirement: NFR-COMPAT-001
Category: Compatibility
Priority: High
Description: Support modern browsers only (latest 2 versions)

Specifications:

• Chrome: Latest 2 versions (currently 120+)
• Firefox: Latest 2 versions (currently 121+)
• Safari: Latest 2 versions (currently 17+)
• Edge: Latest 2 versions (currently 120+)

Acceptance Criteria:

• Game works correctly on all supported browsers
• Visual consistency across browsers
• Performance parity across browsers
• No browser-specific bugs

Testing Approach:

• Manual testing on each supported browser
• Cross-browser compatibility testing
• Visual regression testing

Web Standards Compliance

Requirement: NFR-COMPAT-002
Category: Compatibility
Priority: Medium
Description: Use modern web standards and APIs

Specifications:

• WebGL 2.0: For rendering (fallback to Canvas 2D if unavailable)
• ES2020: Modern JavaScript features
• localStorage: For data persistence
• requestAnimationFrame: For game loop

Acceptance Criteria:

• Uses standard web APIs only
• No proprietary browser features
• Graceful degradation for missing features
• Feature detection before use

Mobile Device Support Requirements

Mobile Optimization

Requirement: NFR-MOBILE-001
Category: Mobile Support
Priority: High
Description: Mobile optimized with touch controls and mobile-friendly UI

Specifications:

• Touch Controls: Swipe gestures for snake direction
• Responsive Design: Adapts to screen sizes (320px - 2560px)
• Mobile UI: Touch-friendly buttons (min 44x44px)
• Orientation: Support both portrait and landscape

Acceptance Criteria:

• Touch controls work smoothly on mobile
• UI elements are touch-friendly (44x44px minimum)
• Game adapts to different screen sizes
• Works in both portrait and landscape modes

Testing Approach:

• Manual testing on iOS and Android devices
• Touch interaction testing
• Screen size compatibility testing

Mobile Performance

Requirement: NFR-MOBILE-002
Category: Mobile Support
Priority: High
Description: Maintain performance on mobile devices

Specifications:

• Frame Rate: 30 FPS minimum on mid-range mobile devices
• Battery Usage: Optimized to minimize battery drain
• Network Usage: Zero network usage during gameplay (offline)
• Storage: < 5MB localStorage usage

Acceptance Criteria:

• 30+ FPS on mid-range mobile devices (iPhone 12, Samsung Galaxy S21)
• Reasonable battery consumption (< 10% per hour)
• No network requests during gameplay
• Minimal storage footprint

Mobile-Specific Features

Requirement: NFR-MOBILE-003
Category: Mobile Support
Priority: Medium
Description: Mobile-specific enhancements

Specifications:

• Haptic Feedback: Vibration on food collection and game over
• Screen Wake Lock: Prevent screen sleep during gameplay
• Touch Gestures: Swipe for direction, tap for pause
• Mobile Menus: Touch-optimized menu navigation

Acceptance Criteria:

• Haptic feedback works on supported devices
• Screen stays awake during gameplay
• Touch gestures are intuitive and responsive
• Menus are easy to navigate on mobile

Accessibility Requirements

Keyboard Navigation

Requirement: NFR-ACCESS-001
Category: Accessibility
Priority: High
Description: Full keyboard navigation support

Specifications:

• Arrow Keys: Snake direction control
• Space: Pause/resume game
• Escape: Return to menu
• Tab: Navigate menu items
• Enter: Select menu items

Acceptance Criteria:

• All game functions accessible via keyboard
• Logical tab order through menus
• Visible focus indicators
• No keyboard traps

Testing Approach:

• Manual keyboard-only testing
• Tab order verification
• Focus indicator visibility testing

Screen Reader Support

Requirement: NFR-ACCESS-002
Category: Accessibility
Priority: Medium
Description: Basic screen reader support

Specifications:

• ARIA Labels: Meaningful labels for UI elements
• Live Regions: Announce score changes and game events
• Semantic HTML: Proper heading structure and landmarks
• Alt Text: Descriptive text for visual elements

Acceptance Criteria:

• Screen readers can announce UI elements
• Score changes are announced
• Game state changes are communicated
• Menu navigation is accessible

Testing Approach:

• Manual testing with NVDA/JAWS/VoiceOver
• ARIA attribute verification
• Screen reader announcement testing

Visual Accessibility

Requirement: NFR-ACCESS-003
Category: Accessibility
Priority: Medium
Description: Visual accessibility considerations

Specifications:

• Color Contrast: Minimum 4.5:1 for text, 3:1 for UI elements
• Font Size: Minimum 16px for body text
• Focus Indicators: Visible 2px outline on focused elements
• Color Independence: Don't rely solely on color for information

Acceptance Criteria:

• Text meets WCAG AA contrast requirements
• Focus indicators are clearly visible
• Game is playable without color perception
• Text is readable at default sizes

Offline Functionality Requirements

Full Offline Support

Requirement: NFR-OFFLINE-001
Category: Offline Functionality
Priority: High
Description: Complete game functionality without internet connection

Specifications:

• Gameplay: Fully functional offline
• Data Persistence: localStorage for all game data
• Assets: All assets bundled, no CDN dependencies
• No Network Calls: Zero network requests during gameplay

Acceptance Criteria:

• Game works with network disabled
• All features available offline
• Data persists across sessions
• No network errors or timeouts

Testing Approach:

• Manual testing with network disabled
• Offline functionality verification
• Data persistence testing

Local Data Management

Requirement: NFR-OFFLINE-002
Category: Offline Functionality
Priority: High
Description: Efficient local data storage and management

Specifications:

• Storage Method: localStorage API
• Data Structure: JSON serialization
• Storage Limit: < 5MB total usage
• Data Validation: Validate on load, handle corruption

Acceptance Criteria:

• Game state persists across browser sessions
• High scores saved locally
• Settings persist across sessions
• Corrupted data handled gracefully

Data Persistence Requirements

Local Storage Only

Requirement: NFR-DATA-001
Category: Data Persistence
Priority: High
Description: localStorage sufficient, no server persistence needed

Specifications:

• Storage API: localStorage only
• Data Types: Game state, high scores, settings
• Storage Keys: Namespaced (nokiaSnake_*)
• Data Size: < 5MB total

Acceptance Criteria:

• All data stored in localStorage
• No server-side persistence
• Data persists across browser sessions
• Storage keys are namespaced

Data Structure

Requirement: NFR-DATA-002
Category: Data Persistence
Priority: Medium
Description: Well-defined data structure for persistence

Specifications:

• Game State: Snake position, food, score, time
• High Scores: Top 10 scores with metadata
• Settings: Controls, volume, visual preferences
• Format: JSON with versioning

Acceptance Criteria:

• Data structure is well-defined
• JSON serialization/deserialization works correctly
• Version field for future migrations
• Data validation on load

Data Integrity

Requirement: NFR-DATA-003
Category: Data Persistence
Priority: High
Description: Ensure data integrity and handle corruption

Specifications:

• Validation: Validate data structure on load
• Corruption Handling: Graceful fallback to defaults
• Backup: No backup mechanism (local only)
• Migration: Version-based data migration support

Acceptance Criteria:

• Invalid data detected and handled
• Corrupted data doesn't crash game
• Fallback to defaults when needed
• Data version tracked for migrations

Security Requirements

Enterprise-Grade Security

Requirement: NFR-SEC-001
Category: Security
Priority: Critical
Description: Maximum security with enterprise-grade measures and audit logging

Specifications:

• Input Validation: Comprehensive validation (SECURITY-05 compliance)
• XSS Prevention: Content Security Policy, input sanitization
• Exception Handling: Secure error handling (SECURITY-15 compliance)
• Audit Logging: Comprehensive logging of security events

Acceptance Criteria:

• All inputs validated and sanitized
• CSP headers configured
• No XSS vulnerabilities
• Security events logged

Testing Approach:

• Manual security testing
• Input validation testing
• XSS vulnerability scanning

Input Security

Requirement: NFR-SEC-002
Category: Security
Priority: Critical
Description: Comprehensive input validation and sanitization

Specifications:

• Keyboard Input: Validate key codes and event types
• Touch Input: Validate touch coordinates and gestures
• localStorage Data: Validate and sanitize on load
• URL Parameters: No URL parameters accepted

Acceptance Criteria:

• All inputs validated before processing
• Invalid inputs rejected gracefully
• No code injection vulnerabilities
• Input validation logged

Audit Logging

Requirement: NFR-SEC-003
Category: Security
Priority: High
Description: Comprehensive audit logging for security events

Specifications:

• Security Events: Log authentication, authorization, validation failures
• User Actions: Log game start, game over, high scores
• System Events: Log errors, exceptions, performance issues
• Log Format: Structured JSON with timestamps

Acceptance Criteria:

• Security events logged with context
• User actions tracked
• System events captured
• Logs include timestamps and severity

Content Security Policy

Requirement: NFR-SEC-004
Category: Security
Priority: High
Description: Strict Content Security Policy configuration

Specifications:

• script-src: 'self' only (no inline scripts)
• style-src: 'self' 'unsafe-inline' (for styled components)
• img-src: 'self' data: (for inline images)
• connect-src: 'none' (no network requests)

Acceptance Criteria:

• CSP headers configured correctly
• No CSP violations in console
• Inline scripts eliminated
• External resources blocked

Scalability Requirements

Code Scalability

Requirement: NFR-SCALE-001
Category: Scalability
Priority: Medium
Description: Maintainable and extensible codebase

Specifications:

• Modularity: Component-based architecture
• Extensibility: Plugin system for future features
• Code Organization: Clear separation of concerns
• Documentation: Inline comments and README

Acceptance Criteria:

• Code is modular and well-organized
• New features can be added easily
• Clear separation between components
• Code is documented

User Load

Requirement: NFR-SCALE-002
Category: Scalability
Priority: Low
Description: Single-player game, no concurrent user concerns

Specifications:

• Concurrent Users: N/A (client-side only)
• Server Load: N/A (no server)
• Database: N/A (localStorage only)

Acceptance Criteria:

• N/A (not applicable for client-side game)

Reliability and Availability Requirements

Error Handling

Requirement: NFR-RELIABLE-001
Category: Reliability
Priority: High
Description: Robust error handling and recovery

Specifications:

• Error Strategy: Silent fail with logging (per functional design)
• Recovery: Fallback to safe state
• User Feedback: Minimal error messages
• Logging: Console logging for debugging

Acceptance Criteria:

• Errors don't crash the game
• Game recovers from errors gracefully
• Errors logged for debugging
• User experience not disrupted

Data Integrity

Requirement: NFR-RELIABLE-002
Category: Reliability
Priority: High
Description: Ensure game state integrity

Specifications:

• State Validation: Validate state on every update
• Corruption Detection: Detect and handle corrupted state
• Recovery: Reset to initial state if unrecoverable
• Backup: No backup mechanism (local only)

Acceptance Criteria:

• Game state always valid
• Corrupted state detected and handled
• Game resets gracefully when needed
• No data loss during normal operation

Uptime

Requirement: NFR-RELIABLE-003
Category: Reliability
Priority: Low
Description: Client-side game, no uptime requirements

Specifications:

• Availability: 100% (client-side, no server dependencies)
• Downtime: N/A (no server)
• Maintenance: N/A (no server)

Acceptance Criteria:

• Game always available (client-side)
• No server dependencies
• No maintenance windows needed

Maintainability Requirements

Code Quality

Requirement: NFR-MAINT-001
Category: Maintainability
Priority: Medium
Description: High code quality standards

Specifications:

• Code Style: Consistent formatting (Prettier)
• Linting: ESLint with recommended rules
• Type Safety: JSDoc comments for type hints
• Documentation: Inline comments and README

Acceptance Criteria:

• Code follows consistent style
• No linting errors
• Functions documented with JSDoc
• README provides setup instructions

Testing

Requirement: NFR-MAINT-002
Category: Maintainability
Priority: Low
Description: Manual testing only (per user requirements)

Specifications:

• Testing Approach: Manual testing by developer
• Test Coverage: N/A (no automated tests)
• Test Documentation: Manual test checklist
• Regression Testing: Manual regression testing

Acceptance Criteria:

• Manual test checklist created
• Developer tests before release
• Critical functionality verified
• No automated test requirements

Deployment

Requirement: NFR-MAINT-003
Category: Maintainability
Priority: Medium
Description: Standard build tool with automated deployment

Specifications:

• Build Tool: Vite (fast, modern)
• Deployment: Automated deployment script
• Environments: Single production environment
• Rollback: Manual rollback if needed

Acceptance Criteria:

• Vite build configuration working
• Automated deployment script created
• Build process documented
• Deployment process documented

Maintenance Expectations

Requirement: NFR-MAINT-004
Category: Maintainability
Priority: Low
Description: One-time development, no ongoing maintenance

Specifications:

• Maintenance: One-time development only
• Bug Fixes: No ongoing bug fix commitment
• Updates: No planned updates
• Support: No ongoing support

Acceptance Criteria:

• Code delivered as-is
• No maintenance plan needed
• No support commitment
• Documentation complete at delivery

Compliance Requirements

Security Baseline Compliance

Requirement: NFR-COMPLY-001
Category: Compliance
Priority: Critical
Description: Full compliance with security baseline rules

Specifications:

• SECURITY-05: Input validation implemented
• SECURITY-15: Exception handling implemented
• All Security Rules: Full compliance with all 15 security baseline rules

Acceptance Criteria:

• All security baseline rules implemented
• Security compliance documented
• Security testing completed
• No security violations

Web Standards Compliance

Requirement: NFR-COMPLY-002
Category: Compliance
Priority: Medium
Description: Compliance with web standards

Specifications:

• HTML5: Valid HTML5 markup
• CSS3: Modern CSS features
• ES2020: Modern JavaScript
• Web APIs: Standard web APIs only

Acceptance Criteria:

• HTML validates
• CSS validates
• JavaScript follows ES2020 standards
• No proprietary APIs used

Performance Benchmarks

Target Metrics

Metric	Target	Measurement Method
Frame Rate	30+ FPS	Browser DevTools Performance tab
Input Latency	< 50ms	Manual testing with timestamp logging
Load Time	< 3s on 3G	Network throttling in DevTools
Bundle Size	< 500KB	Build output analysis
Memory Usage	< 50MB	DevTools Memory profiler
localStorage Usage	< 5MB	localStorage size monitoring

Performance Testing

• Manual Testing: Developer tests on target devices
• Profiling: Browser DevTools performance profiling
• Monitoring: Console logging for performance metrics
• Optimization: Iterative optimization based on profiling

Summary

This Nokia Snake game has comprehensive NFR requirements covering:

• Performance: 30 FPS minimum, fast load times, efficient memory usage
• Compatibility: Modern browsers only (latest 2 versions)
• Mobile: Mobile optimized with touch controls
• Accessibility: Basic keyboard navigation and screen reader support
• Offline: Full offline functionality with localStorage
• Security: Enterprise-grade security with audit logging
• Maintainability: Standard build tool, manual testing, one-time development

All requirements align with the functional design and support the overall game architecture.