Tetris Clone

# Tetris Clone PRD

## Overview
Build a fully playable Tetris clone featuring all seven standard tetrominoes, a scoring system with level progression, and polished game mechanics including hold piece and ghost piece.

## Requirements
- Standard 10x20 game grid
- All 7 tetromino pieces (I, O, T, S, Z, J, L) with correct colors
- Piece rotation with wall kick support
- Soft drop (hold down arrow) and hard drop (space bar)
- Line clearing with visual animation
- Scoring system with bonuses for single, double, triple, and Tetris (4 lines)
- Level progression with speed increase every 10 lines cleared
- Next piece preview showing the next 3 upcoming pieces
- Hold piece functionality (press C to hold/swap)
- Ghost piece showing where the current piece will land
- Game over detection when pieces stack to the top
- Pause and resume functionality
- High score board persisted to localStorage
- Keyboard controls (arrows for movement, space for hard drop, C for hold, P for pause)
- Start screen and game over screen with score display

## Tech Stack
- JavaScript with HTML5 Canvas
- No game engine libraries

## Scoring Criteria
- **Functional (40%)**: Core Tetris gameplay works, pieces rotate, lines clear, scoring tracks correctly
- **Quality (20%)**: Smooth animations, no visual glitches, responsive controls
- **Fidelity (25%)**: All features present including hold, ghost piece, next preview, and levels
- **Speed (15%)**: Time bonus