A good game teaches you how to play it

What you eventually discover as you continue to play is that Portal is a game about escaping from rooms that operate according to rules you are unaware of. You learn that each room is a puzzle, increasingly booby-trapped, and the game requires you to understand more and more complex physics in order to get out. If you don’t teach yourself the physics of each new room— that is, if you don’t learn the rules of the game—you’ll be stuck there forever, listening to the AI system repeat h...