If i am not mistaking, Bloodborne has kind of the world changing sanity meter in an open world enviroment that you guys mentioned. Also i think, Call of Cthulhu: Dark Corner of the Earth made use of a brilliant sanity system, throwing the player back in mader and uglier versions of the time the PC spend in the asylum, when the player deliberatly looked at dead bodys and so forth or when he was exposed to unnatural things (like Cthulian artifacts). And finally, there is your very own Yahtzee and his new game consuming shadows.
Dammit, it's no good dropping game-ruining spoilers and then saying "spoilers" afterwards like that. I played KOTOR years ago, but that's just not cool. Especially since this KOTOR2 update is exactly the sort of thing which might attract people who never played it before.
might be a good example for the insanity system without a meter.
HOW can you discuss sanity systems in games and NOT bring up Eternal Darkness: Sanity's Requiem? That game screwed with the player in a truly unique way, (tiny spoiler ahoy) you quickly became so used to bizzare-but-harmless nonsense happening, that when a cluster of screaming monsters explode- killing you with them- you think your character is alive and the explosion didn't REALLY happen. it was a hallucination. Game over, Reload last save [Y] [N]