I'd go further than that. I'd say a game is complete when its author decides it is. There is always, always something more that could be added to a game. The only reason that commercial games appear more "completed" is because they have a manager guy who sets a deadline and makes people put an end-sequence or a certain amount of quests or gameplay hours or whatever into the game, to call it complete by his standards. In the world of indie games, the complete/incomplete line is all the more blurry because there's nobody with a MBA to arbitrate completeness for you. =D