Digital Blueprinting with Kiro's Spec-Driven Development

One of Kiro’s true power lies in its spec-driven development approach, a structured methodology designed to transform vague ideas into code with clarity and consistency. We will walk through how to leverage core spec files that is requirements.md, design.md, and tasks.md

Why Spec-Driven Development?

Traditional development often involves jumping straight into code, leading to scope Creep with requirements change mid development, misunderstandings with developers and stakeholders aren't on the same page, documentation Drift as Code evolves, but the docs don't. "Vibe Coding" AI generates code, but without a clear architectural vision.

Kiro seeks to combats these issues by establishing a clear, AI parsable contract for your project from the outset. This allows it to act as a true copilot, ensuring your components align with your overall vision.

I am going to demonstrate creating a Spec documents, through the creation of a simple stick fighting game.

Step 1: Defining Your Vision with requirements.md

This is where your project begins. This is your single source of truth for what your system needs to do, leveraging this file to generate user stories, acceptance criteria, and a foundational understanding of your application.

How to Implement It:

Start with Core Gameplay: Begin with a clear statement of what makes your fighting game unique.

A web-based stickman fighting game where players control stick figure characters 
in combat scenarios. The game will feature simple controls, engaging combat mechanics, 
and smooth animations to provide an entertaining fighting experience directly in 
the browser.

Break Down into User Stories (EARS Notation Recommended): Use the EARS (Easy to Understand, Atomic, Readable, Specific) notation or a similar structured format to define individual features from a user's perspective. Include clear acceptance criteria.

## Requirements

### Requirement 1

**User Story:** As a player, I want to control a stickman character with keyboard inputs, so that I can move and perform actions in the fighting arena.

#### Acceptance Criteria

1. WHEN the player presses arrow keys THEN the stickman SHALL move left, right, jump, or crouch accordingly
2. WHEN the player presses attack keys THEN the stickman SHALL perform punch or kick animations
3. WHEN the player presses block key THEN the stickman SHALL enter defensive stance
4. WHEN multiple keys are pressed simultaneously THEN the system SHALL handle combination moves appropriately

### Requirement 2

**User Story:** As a player, I want to engage in combat with an opponent, so that I can experience competitive fighting gameplay.

#### Acceptance Criteria

1. WHEN two stickman characters are in proximity THEN attacks SHALL be able to connect and deal damage
2. WHEN a character's health reaches zero THEN the system SHALL declare the opponent as winner
3. WHEN an attack connects THEN the system SHALL provide visual feedback and reduce target's health
4. WHEN characters collide THEN the system SHALL handle collision detection accurately

### Requirement 3

**User Story:** As a player, I want to see smooth animations and visual effects, so that the fighting feels responsive and engaging.

#### Acceptance Criteria

1. WHEN a character performs any action THEN the system SHALL display appropriate stick figure animations
2. WHEN attacks connect THEN the system SHALL show impact effects or particle effects
3. WHEN characters move THEN the animations SHALL be fluid at 60 FPS or higher
4. WHEN the game runs THEN all animations SHALL be synchronized with game logic

### Requirement 4

**User Story:** As a player, I want a simple game interface, so that I can easily understand the game state and controls.

#### Acceptance Criteria

1. WHEN the game loads THEN the system SHALL display health bars for both players
2. WHEN the game is in progress THEN the system SHALL show current round information
3. WHEN the game ends THEN the system SHALL display winner announcement and restart option
4. WHEN the player needs help THEN the system SHALL provide accessible control instructions

### Requirement 5

**User Story:** As a player, I want the game to work reliably in my web browser, so that I can play without technical issues.

#### Acceptance Criteria

1. WHEN the game loads in a modern web browser THEN it SHALL run without requiring additional plugins
2. WHEN the browser window is resized THEN the game SHALL maintain proper aspect ratio and playability
3. WHEN the game runs for extended periods THEN performance SHALL remain stable without memory leaks
4. WHEN network connectivity is poor THEN the game SHALL still function as a local experience

Clarify Technical Requirements: Include platform compatibility and performance targets.

## Technical Requirements

### Platform Support
1. Work on modern web browsers (Chrome, Firefox, Safari, Edge)
2. Responsive design that adapts to different screen sizes
3. Mobile device support

### Performance
1. Maintain 60 FPS on mid-range devices
2. Optimize animations and physics calculations
3. Efficient memory usage

### Technology Stack
1. HTML5, CSS3, and JavaScript
2. Canvas or WebGL for rendering
3. Potential use of game frameworks (optional)

Step 2: Architecting Your Game with design.md

With clear requirements, we move into the design phase. The design.md file (or a collection of design files within a design/ directory) outlines how your system will meet those requirements. This is where you define architecture, data models, API schemas, and more.

How to Implement It:

High-Level Architecture: Describe the overall system components

# Design Document

## Overview

The stickman fighting game will be built as a client-side web application using HTML5 Canvas and JavaScript. The architecture follows a component-based game engine pattern with clear separation between rendering, game logic, input handling, and animation systems. The game will use a fixed timestep game loop for consistent physics and animation, with interpolation for smooth 60 FPS rendering.

## Architecture

### Core Architecture Pattern
- **Entity-Component System (ECS)**: Characters and game objects are entities with components for position, health, animation, collision, etc.
- **Game Loop**: Fixed timestep update loop with variable timestep rendering
- **State Management**: Finite state machine for game states (menu, playing, paused, game over)
- **Event-Driven Input**: Keyboard input system with event queuing and combination detection

### Technology Stack
- **Rendering**: HTML5 Canvas 2D API for graphics and animations
- **Language**: Vanilla JavaScript (ES6+) for maximum browser compatibility
- **Build**: No build system required - direct HTML/JS/CSS files
- **Animation**: Custom sprite-based animation system with frame interpolation

Components and Interfaces: Characters and game objects are entities with components for position, health, animation, collision, etc

## Components and Interfaces

### Game Engine Core

```javascript
// Main game engine interface
class GameEngine {
  constructor(canvas)
  start()
  stop()
  update(deltaTime)
  render(interpolation)
}

// Character entity with component composition
class Character {
  constructor(x, y, playerIndex)
  // Components
  position: PositionComponent
  health: HealthComponent
  animation: AnimationComponent
  collision: CollisionComponent
  input: InputComponent
}

// Character states for animation and behavior
enum CharacterState {
  IDLE, WALKING, JUMPING, CROUCHING, 
  PUNCHING, KICKING, BLOCKING, HURT, DEAD
}

class InputManager {
  constructor()
  bindKeys(playerIndex, keyMapping)
  getInputState(playerIndex)
  handleKeyDown(event)
  handleKeyUp(event)
}

// Input mapping for two players
const PLAYER_CONTROLS = {
  PLAYER1: { left: 'ArrowLeft', right: 'ArrowRight', up: 'ArrowUp', down: 'ArrowDown', punch: 'KeyZ', kick: 'KeyX', block: 'KeyC' },
  PLAYER2: { left: 'KeyA', right: 'KeyD', up: 'KeyW', down: 'KeyS', punch: 'KeyJ', kick: 'KeyK', block: 'KeyL' }
}

class AnimationManager {
  constructor()
  createAnimation(name, frames, duration, loop)
  playAnimation(character, animationName)
  update(deltaTime)
}

class SpriteRenderer {
  constructor(canvas)
  drawStickman(character, interpolation)
  drawUI(gameState)
  drawEffects(effects)
}

Error handling, Testing strategy and Implementation Architecture

## Error Handling

### Input Error Handling
- **Invalid Key Combinations**: Ignore conflicting inputs (e.g., left + right simultaneously)
- **Rapid Key Presses**: Implement debouncing for attack inputs to prevent spam
- **Browser Compatibility**: Feature detection for Canvas API and fallback messaging

### Game Logic Error Handling
- **Animation Errors**: Default to idle animation if animation file missing or corrupted
- **Collision Edge Cases**: Boundary checking to prevent characters from moving outside arena
- **Performance Degradation**: Frame rate monitoring with automatic quality reduction if needed

### Rendering Error Handling
- **Canvas Context Loss**: Detect context loss and reinitialize rendering system
- **Memory Leaks**: Proper cleanup of animation frames and event listeners
- **Browser Resize**: Responsive canvas sizing with aspect ratio preservation

## Testing Strategy

### Unit Testing
- **Character Movement**: Test position updates, boundary constraints, and state transitions
- **Collision Detection**: Verify hitbox calculations and attack/defense interactions
- **Animation System**: Test frame progression, loop behavior, and state synchronization
- **Input Processing**: Validate key mapping, combination detection, and player separation

### Integration Testing
- **Game Loop**: Test update/render cycle timing and state consistency
- **Character Interactions**: Verify combat mechanics, health reduction, and win conditions
- **UI Integration**: Test health bar updates, game state displays, and user feedback

### Performance Testing
- **Frame Rate Consistency**: Monitor FPS under various load conditions
- **Memory Usage**: Track memory allocation and garbage collection patterns
- **Browser Compatibility**: Test across Chrome, Firefox, Safari, and Edge

### Visual Testing
- **Animation Smoothness**: Verify 60 FPS rendering and frame interpolation
- **Collision Feedback**: Test visual effects for hits, blocks, and impacts
- **UI Responsiveness**: Ensure interface elements update correctly with game state

Implementation Architecture

File Structure

stickman-fighting-game/
├── index.html
├── css/
│   └── game.css
├── js/
│   ├── engine/
│   │   ├── GameEngine.js
│   │   ├── InputManager.js
│   │   └── AnimationManager.js
│   ├── entities/
│   │   ├── Character.js
│   │   └── Effect.js
│   ├── systems/
│   │   ├── PhysicsSystem.js
│   │   ├── CollisionSystem.js
│   │   └── RenderSystem.js
│   └── main.js
└── assets/
    └── sounds/ (optional for future enhancement)

Rendering Pipeline

1. Clear Canvas: Clear previous frame

2. Background: Draw arena background

3. Characters: Render stickman sprites with current animation frame

4. Effects: Draw particle effects and impact animations

5. UI: Overlay health bars, round info, and game state

6. Debug: Optional collision box visualization

Step 3: Executing the Plan with tasks.md

This is where Kiro breaks down the design into actionable, atomic steps for implementation. tasks.md typically isn't something you write from scratch, which it then generates it based on your requirements.md and design.md. Your role here is to review, refine, and track progress.

How to Leverage It:

Review Generated Tasks: Once you've created requirements and design documents, break them down into specific tasks:

# Implementation Plan

- [ ] 1. Set up project structure and core HTML/CSS foundation
  - Create index.html with canvas element and basic page structure
  - Create game.css with responsive canvas styling and UI layout
  - Set up file directory structure for organized code modules
  - _Requirements: 5.1, 5.2_

- [ ] 2. Implement core game engine and loop system
  - Create GameEngine.js with fixed timestep game loop and requestAnimationFrame
  - Implement game state management (MENU, PLAYING, PAUSED, GAME_OVER)
  - Add canvas context initialization and error handling for context loss
  - Write unit tests for game loop timing and state transitions
  - _Requirements: 5.1, 5.3, 3.3_

- [ ] 3. Build input management system
  - Create InputManager.js with keyboard event handling and key mapping
  - Implement two-player control schemes with configurable key bindings
  - Add combination key detection and input debouncing for attacks
  - Write unit tests for input processing and player separation
  - _Requirements: 1.1, 1.2, 1.3, 1.4_

- [ ] 4. Create character entity and component system
  - Implement Character.js with position, health, and state components
  - Create character state enumeration (IDLE, WALKING, JUMPING, etc.)
  - Add character initialization with starting positions and properties
  - Write unit tests for character creation and component management
  - _Requirements: 1.1, 2.2_

- [ ] 5. Implement basic character movement and physics
  - Add movement logic for left/right walking and jumping mechanics
  - Implement gravity system and ground collision detection
  - Create boundary constraints to keep characters within arena
  - Write unit tests for movement calculations and boundary checking
  - _Requirements: 1.1, 5.2_

Starting your Implementation Plan

The Power of Synchronization: Living Documentation

One of Kiro's most powerful features is its ability to keep these specification files in sync with your codebase.

• Changes in Code -> Updates in Specs: If you decide to change an API endpoint directly in your code, then it prompts you to update design.md accordingly, or even suggest the change automatically.

• Changes in Specs -> Updates in Code: If you modify a data model in design.md, it then can suggest or even apply the necessary code changes (e.g., updating TypeScript interfaces, DynamoDB table definitions).

This "living documentation" ensures that your specifications always reflect the current state of your application, reducing maintenance overhead and eliminating the classic problem of outdated documentation.

Embracing Spec-Driven Workflow

Mastering requirements.md, design.md, and tasks.md is key to harnessing the full potential of Kiro. By embracing this structured, spec-driven workflow, you'll benefit from Increased Clarity where everyone is aligned on what's being built and how. Reduced Errors you can validate code against the specs, catching inconsistencies early. Faster Development of accurate code and infrastructure from precise instructions, and your documentation stays evergreen, making future changes easier.

Join me on this journey as I create my stick game, step by step, spec by spec, and discover the benefits of intentional, efficient development with Kiro.

Lets Connect - Lewis Sawe: LinkedIn
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