Read the current directory structure, check if phaser.min.js exists, then create a top-down alien shooter game. The game should include: WASD movement, mouse aiming and shooting, wave-based alien enemies, health system, score system, and gradually increasing difficulty. Use Phaser's graphics API to generate all game art, no external resources.  
First look at the current directory to confirm phaser.min.js is present, then start building the game.

Good, phaser.min.js exists. Now I need to create a complete single-page HTML file that includes:

1. CSS in a <style> tag
2. HTML structure
3. JavaScript using Phaser with:
   - WASD movement
   - Mouse aiming and shooting
   - Wave-based aliens
   - Health system
   - Score system
   - Increasing difficulty
   - All graphics procedurally generated using Phaser's graphics API

Let's create a comprehensive alien shooter game. I'll use:
- Phaser.Graphics for generating all sprites
- Player tank that moves with WASD and aims with mouse
- Projectiles with collision detection
- Alien enemies that spawn in waves and move toward the player
- Health and score UI
- Difficulty scaling based on wave number
- Particle effects for explosions
- Sound effects (if possible with procedural audio, or just visual feedback)

The game structure will be:
- Boot state: Initialize loading screen
- Game state: Main gameplay
- Game over state: When player dies

Let me write this as a single HTML file.

Great! I've created a complete top-down alien shooter game. Now let me verify the file was created successfully and test it.

Good! The file has been created successfully. Let me verify it works by checking if it's a valid HTML file by looking at the beginning of the file.

Perfect! The file has been created successfully. Let me verify the complete structure by checking the end of the file as well to make sure it's a complete HTML file.

Perfect! The complete game has been created successfully. Let me provide a summary of what I've built.