Game programming lesson

Usage:

npm install
npm start

Then visit:

• http://localhost:3000/demos/brick-breaker to play the Brick breaker game,
• http://localhost:3000/demos/race to play a thrilling racing game (arrows for player one, WASD for player two),
• http://localhost:3000/demos/adventure to play a clone of a clone of the old "Adventure" game.