§69

We are not ignorant of the boundaries of the concept 'game' because no boundaries have been drawn (the meaning of a word is not something hidden from us that we might uncover/discover).

We can't tell others exactly what a game is (where exactly the boundary lies between games and non-games) but this should not worry us - the term is clearly usable. What we can do is point to a variety of things that are games (monopoly, football, chess, Halo) and say, 'this is a game, this is a game, and this is a game - and other similar things are called games'.