Nintendo patented the ‘sanity system’ from Eternal Darkness, according to a page on the US Patent website. Being that the patent assignee is Nintendo of America, that seems to rule out the possibility of its usage in any future games from Silicon Knights (or anyone else, for that matter), as they’ve decided to move on to other console development than Nintendo. The patent states:
A video game and game system incorporating a game character’s sanity level that is affected by occurrences in the game such as encountering a game creature or gruesome situation. A character’s sanity level is modified by an amount determined based on a character reaction to the occurrence such as taking a rest or slowing game progress and/or an amount of character preparation. That is, if a character is prepared for the particular occurrence, the occurrence may have little or no affect on the character’s sanity level. As the character’s sanity level decreases, game play is effected such as by controlling game effects, audio effects, creating hallucinations and the like. In this context. the same game can be played differently each time it is played.