There are two other ways for the game to end.
1. The attacker is forced to give up another letter, but cannot, because that's the end of the word. This happens very infrequently (because if the current letters make a word, it is often very quickly clued, usually as "That" or something similar).
2. The attackers do not know the word the defender has in mind. At this point, everyone sits around awkwardly for a few minuets until it's clear that nobody knows the word, and then the defender languishes in shame for the next three hours.
