Doubting that there was a real game involved, an IGN forumite decided to check up on Nibris's claim that their mysterious Sadness was going to be co-developed and published by Frontline Studios. The conclusion supports the claim but may not justify the meanness.
Basically, he contacted Frontline to see if they were actually publishing Sadness and if it really existed. Frontline responded that they were "no longer interested in developing Sadness game based on Nibris' concept." This sort of makes it sound like there never was a game, and now there may never be. We might disagree with the poster's tactic, because it's kind of rude to openly doubt the existence of a game in an interview with its erstwhile publisher, but it sounds like his doubts were not misplaced.