Quantic Dream's Heavy Rain wasn't expected to be as successful as it was, according to creator David Cage. The wannabe film director has said that Heavy Rain was given a lowball sales estimate, but that the PS3 exclusive sold four times as many copies as anticipated.
The NPD claims the game sold around 400,000 copies in the US, which isn't the world's biggest success, but it surpassed Sony's expectations. In Europe and Japan, the game became a big hit.
As much sh*t as I got for suggesting that the game was "good" and not "perfect", I am glad that the title performed above expectations. At the very least, it demonstrates that not every game has to be an FPS or a casual dancing game in order to succeed, and hopefully publishers take note of that.