The Magic Circle as we discussed in class is more of a frame of mind. It is not necessarily a physical space or circle, but it is the area in which the rules of the game apply.
Pacing is important in game design obviously, but specifically it plays a big role in how likeable the game itself is. If a game is too slow paced, it can bore people or disinterest them. If a game is too fast, the game has no real incentive to play and can be found pointless, not entertaining. There has to be a balance in the pacing to allow for some strategy but also some gratification that allows the users or players to feel like they’re winning in some sense or at least have the chance to win.