FortressCraft is the first Xbox Live Indie Game to break $1 million in sales, and I wouldn't be surprised if it's the last. Unless, of course, FortressCraft Chapter 2 ever comes out.
ProjectorGames was able to recognize a need of the market -- in this case, Xbox 360 players wanting a certain block-centric experience readily available in many forms on PC -- and capitalize on it. Nothing wrong with that. Although I will say it doesn't interest me personally.
350,000 of you, however, felt differently. Shame that this level of success is an outlier rather than the norm.