Typing Race Game

# Typing Race Game PRD

## Overview
Build a competitive typing race game where players type against AI opponents on a visual race track, with real-time WPM tracking, multiple text categories, and a leaderboard system.

## Requirements
- Race track visualization with a car or avatar that moves forward as the player types
- Text passage displayed with the current word highlighted
- Real-time WPM (words per minute) and accuracy percentage during the race
- Multiple text categories to choose from: quotes, code snippets, prose, and technical writing
- AI opponents with varying speeds ranging from 40 to 120 WPM
- Countdown start sequence (3, 2, 1, GO!) before each race begins
- Car crosses the finish line when the text is fully typed
- Results screen showing WPM, accuracy, rank among racers, and total time
- Ghost race mode to race against your previous best performance
- Practice mode with no race — just type freely to warm up
- Custom text input mode where the player provides their own passage
- Mistake penalty that visually slows the car down on errors
- Leaderboard tracking best times and WPM per category in localStorage
- Sound effects for engine revving, typing, and crossing the finish line
- Responsive design that works on both desktop and mobile
- Streak bonus for consecutive correctly typed words

## Tech Stack
- HTML, CSS, JavaScript (vanilla or any framework)
- Canvas or DOM-based rendering for the race track — no game engine libraries

## Scoring Criteria
- **Functional (40%)**: Typing detection, WPM calculation, race track movement, and AI opponents all work correctly
- **Quality (20%)**: Smooth animations, accurate timing, handles edge cases (backspace, fast typing), clean code
- **Fidelity (25%)**: All features implemented including ghost race, practice mode, sound effects, leaderboard
- **Speed (15%)**: Time bonus