The response will include the thinking and the final answer.

The user wants a single-page web app (index.html) that uses phaser.min.js (already present) to build a Mario-style side-scrolling platformer. All graphics must be procedurally generated (no external assets). The file should be self-contained with inline CSS and JS.

Let me first check if phaser.min.js exists in the current directory, then build the game.

Key features needed:
1. Side-scrolling platformer
2. Run and jump
3. Scrolling platforms
4. Stomp enemies
5. Collect coins
6. Goal flag
7. Procedurally generated graphics only

I'll use Phaser 3's graphics primitives to draw everything.

Let me plan the game:
- Player: a rectangle character that can move left/right and jump
- Platforms: green/brown rectangles
- Enemies: red rectangles that move back and forth (like goombas)
- Coins: yellow circles
- Goal flag: a pole with a flag
- Camera follows the player
- Score display
- Multiple platforms at different heights

Let me write this out.

No constraints on content.

Let me create a full Mario-style platformer with Phaser 3. I'll use procedurally generated graphics (no external assets). The game needs:
- Player character that can run and jump
- Scrolling platforms
- Enemies to stomp
- Coins to collect
- Goal flag at the end
- All graphics generated procedurally using Phaser graphics API

Let me write a comprehensive game.

I NEVER include my reasoning in the response, only in the thinking section.

Now, let's build the platformer.

Requirements:
- Single file: index.html
- CSS in <style>, JS in <script>, inline
- No external resources except phaser.min.js loaded via <script src="phaser.min.js">
- Phaser 3 global (Phaser)
- Side-scrolling platformer Mario style
- Run and jump across scrolling platforms
- Stomp enemies, collect coins, reach goal flag
- Procedurally generated graphics (no external images/audio)

I'll build a complete Phaser 3 platformer with:
- Player character (procedurally drawn with graphics)
- Scrolling level with platforms
- Coins to collect
- Enemies that patrol and can be stomped
- Goal flag at the end
- Score display
- Camera follows player

Let me write the full index.html.

I must not include the  tags in my final response.

Wait, the user's request is to build a single-page web app using Phaser.js. The file index.html has been written. Let me verify it works by checking the phaser.min.js exists and the file is well-formed.

Actually, I should test it with a quick check.