Where is it? Find the tutorial at: https://docs.repl.it/tutorials/07-building-a-game-with-pygame
What is it? A beginner's introduction to PyGame. You'll build your own juggling game with a basic game loop and moving tennis balls that the player can click on to throw.
What do you need to follow? A bit of Python experience is ideal, but you should be able to keep up even without it. You'll do everything from your browser so no Python set up is required. You can create a free account on Repl.it to save and share your code.