How many copies does a game have to be sold for it to considered successful?

[largedarryl]

mesoteto said:
i only see it as being a success if it moves enough to cover marketing/dev cost

I'd think a few more copies need to be sold to be considered succesful.  I would think a game needs to turn a profit, not just cover dev/advertising costs.  I'd think a company that creates games that are only capable of meeting dev costs would lose investors and publishers really quick.