 The limits of skill are also very important. A lot of people, when they start getting good at games, expect that they'll start winning games a lot more often. That is true. But for example, if you play poker, the percentage that you'll win in terms of hands over everybody else, even if you're a very skilled poker player, is in the single digits. Being very good at poker gives you a relatively tiny edge among other pretty good players. You'll crush people with no idea, but you're going to lose a lot of hands. In poker, you're going to fold most of the time. So when you lose games, and when you design a game, you need to really pay attention to what is that percentage, because that determines who's going to play your game, what the experience of losing is like.