Here's something I wish more game designers understood: If you put an interaction in your game, I am going to interact with it. Anytime a game responds to its players, the rats -- or at least this rat -- are going to press the lever for more cocaine pellets. Jenova Chen, during a talk about the design of Journey a couple years ago at the Game Developers Conference, put it this way: "If you give me a gun, and you lock me up with another guy in a room, I think I'm going to use it someday."