Eternal Darkness was the first game published by Nintendo, as opposed to a thirdparty developer, to be rated ‘M’ for Mature by the ESRB. A sequel was planned, reportedly to be launched alongside the Wii U, but was cancelled due to Silicon Knight’s legal entanglement with Epic Games.
Are you wondering why you haven’t seen the Sanity system make an appearance in more videogames? It turns out Nintendo actually patented it, restricting other companies from making use of the concept. So wide-reaching is this patent that very few developers have dared include anything even remotely similar to it.