The ES modules approach was overengineered and broken:
- Import maps failed silently
- Game engines couldn't find window.App
- Nothing was responsive

New approach: everything in index.php + one CSS file.
- Loads public/js/app.js (game engines need App.fetch, App.toast etc)
- Simple defineScreen() router — no modules, no imports, no build step
- Chess game works: loads chess.min.js + board.js + game.js, enters immersive mode
- Ludo/Domino/Backgammon lobbies create games via API
- All screens responsive (max-width adapts, clamp() on hero heights)
- Visual identity from DESIGN.md: game-specific gradients, 20px radius cards, gold brand
- Header shows level + coins + gems (the game currencies, not chess ELO)
- DESIGN.md added as the visual specification document
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>