From Idea to Detailed Product Spec

Building SET Game: A Systematic Approach

The Starting Vision

Core Idea: A mobile-first multiplayer SET card game for kids

Key Principles from Day One:

• Zero-friction entry (WhatsApp invite links, no passwords)
• Mobile-first design (iPhone SE as baseline)
• Real-time competitive multiplayer (up to 4 players)
• All cards always visible (no scrolling)

The Methodology: Comprehensive Planning Before Coding

Phase 1: Product Foundation

User Stories & Requirements

We started by defining the complete user journey:

• Player personas (kids as primary users)
• Core user flows (joining games, gameplay, social features)
• Feature prioritization (MVP vs future enhancements)
• Success metrics (engagement, accessibility)

Output: Clear understanding of what we're building and why

Phase 2: Design System

Visual & Interactive Design

With user needs defined, we designed:

• 12 complete UI screens with wireframes
• Responsive card layout system (120px → 70px auto-shrinking)
• Color schemes and typography for kids
• Avatar system and visual feedback
• Touch-optimized interactions for mobile

Output: Detailed mockups showing how users experience the product

Phase 3: Technical Architecture

System Design & Infrastructure

Technical decisions driven by product requirements:

• Stack selection: React + Node.js + PostgreSQL + Redis
• Real-time architecture: WebSocket for 4-player synchronization
• Mobile optimization: Responsive breakpoints and performance
• Scalability planning: Game state management with Redis

Output: Blueprint for how to build it technically

The Breakthrough: Cursor Rules Files

Why 16 Separate Files?

Instead of one massive document, we created domain-specific guidance files:

Each file serves a specific purpose:

• Focused context for AI-assisted development
• Easy to update individual components
• Clear separation of concerns
• Modular and maintainable documentation

The 16 Cursor Rules Files

Product & Requirements (3 files)

1. User Stories - Complete user journey and features
2. Product Requirements - Core functionality and constraints
3. Success Metrics - How we measure quality

Design System (4 files)

1. Design System - Colors, typography, spacing
2. UI Components - Reusable component library
3. Screen Wireframes - All 12 screens detailed
4. Responsive Design - Mobile-first breakpoints

The 16 Cursor Rules Files (continued)

Technical Specifications (5 files)

1. Architecture Overview - System design and stack
2. Frontend Specs - React components and state
3. Backend Specs - API endpoints and services
4. Database Schema - PostgreSQL tables and relationships
5. Real-time System - WebSocket implementation

The 16 Cursor Rules Files (continued)

Implementation Guidance (4 files)

1. Development Workflow - Git strategy and testing
2. Code Standards - Naming conventions and patterns
3. Performance Guidelines - Mobile optimization rules
4. Deployment Guide - Production setup and monitoring

Total: 120KB+ of comprehensive specifications

Key Principles in Our Approach

1. Mobile Constraints Drive Design

• Started with iPhone SE dimensions
• Designed the auto-shrinking card mechanism
• Ensured no scrolling requirement
• Touch-first interactions

2. Zero-Friction Philosophy

• No passwords or complex authentication
• WhatsApp invite links for instant join
• Name + avatar selection only
• Kid-friendly at every step

Key Principles in Our Approach (continued)

3. Real-Time First

• WebSocket architecture from the start
• 4-player simultaneous gameplay
• Instant feedback and synchronization
• Conflict resolution strategies

4. Comprehensive Before Code

• 100+ hours of planning and specification
• Every screen wireframed
• Every API endpoint documented
• Every edge case considered

The AI-Assisted Development Strategy

Why This Level of Detail Matters

Traditional Development:

• Developer interprets vague requirements
• Design and technical decisions made ad-hoc
• Lots of back-and-forth and rework

Our Approach with Cursor + AI:

• AI coding assistant has complete context
• Specifications guide every implementation decision
• Consistency across all components
• Faster development with fewer mistakes

Example: The Card Layout Challenge

Problem Statement

Mobile screens are small. SET requires 12-21 cards visible simultaneously.

Our Specification Process

1. User Story: "As a player, I need to see all cards at once to find SETs quickly"

2. Design Constraint: No scrolling, always visible

3. Technical Solution:

Cards: 120px → 70px (auto-shrink)
12 cards: 120px each (comfortable)
21 cards: 70px each (still playable)

4. Cursor Rules File: Exact breakpoints, CSS grid specs, animation timing

Benefits of This Approach

Speed & Quality

• AI can implement features end-to-end with proper context
• Consistency across codebase
• Fewer bugs from misunderstood requirements

Maintainability

• Complete documentation for future updates
• Easy onboarding for new developers
• Clear rationale for every decision

Flexibility

• Can update individual specification files
• Easy to add features with similar detail
• Clear dependency mapping

The Results

From Idea to Ready-to-Build

Timeline: Comprehensive planning phase completed

Deliverables:

• ✅ 16 detailed cursor rules files (120KB+)
• ✅ Complete user journey mapped
• ✅ All 12 screens wireframed
• ✅ Technical architecture finalized
• ✅ Database schema designed
• ✅ API endpoints documented

Next Step: Domain acquisition → Development starts

Lessons Learned

1. Invest in Planning

Heavy upfront specification work pays dividends in development speed and quality

2. Structure for AI Assistance

Breaking specifications into focused files makes AI coding assistants dramatically more effective

3. Mobile Constraints Are Good

Designing for mobile-first forced better solutions (like auto-shrinking cards)

4. Document Decisions

Every architectural choice has rationale preserved in cursor rules files

The Path Forward

Development Phase

With 16 comprehensive cursor rules files, development becomes:

• Guided: Clear specifications for every feature
• Efficient: AI assistant has complete context
• Consistent: Unified patterns across codebase
• Quality: Edge cases and requirements already considered

The Vision Realized

From a simple idea to a fully-specified product ready for development — all before writing production code.

Key Takeaway

The secret isn't just planning — it's planning for AI-assisted development

By creating comprehensive, structured, domain-specific specification files, we transformed AI coding assistants from helpful tools into highly effective development partners.

16 cursor rules files = The bridge between human vision and AI implementation