Shacknews has detail on Darkness, a survival horror game that was in the works at id Software for 18 months before the project was cancelled due to similarities with DOOM 3. The poor commercial track record of survival horror games also factored into the decision, they were told by John Carmack, but apparently the game's dark environments and ambush gameplay "would have been keeping Doom 3's faults," he told them, saying complaints about the "contrived nature of monsters hiding in closets" were "completely valid." The article also touches on how they broached the topic of cancelling the game after so much effort had already been expended on development.