Gin no Saji aka Silver Spoon gave me an idea of how Cognitive Dissonance can be healthy. The anime is about farming, and dwelt on the internal conflict of being a farmer - taking care of animals and killing them to make a living and eating them. Doubt is a virtue in some Philosophical disciplines which I wont go in to.
Today's (at the time I wrote this) morbid reality (reddit thread) got me thinking of declining Mental Health Care in many countries (looking at my own country the anecdotes of spiraling depression, debt and death seems to grow and the current traditional coping mechanisms, which is to brush it aside to buy time, does not work).
Since I'm a gamer typically I research and build the data into a narrative for it to make sense. Particularly the horror is tackling Mental Health Care. I'm imagining an investigation following the closing of many such care facilities, following the lives of these people which needed this system, and how it affects the psyche of a community as this psychosis is transmitted by the consequences of their actions. Madness, as a source of fear for the Players, is tackled in Kenneth Hite's GURPS Horror, and a bit in Lisa J. Steele's GURPS Mysteries (GURPS Mysteries and Horror is for any game system methodology and exposure to them will definitely arm the GM with more options and techniques in greater player engagement)
One can basically have a mystery where players are caught in the middle of the ethical dilemma that pulls in many directions (which is par for the course in engaging games). Particularly when they deal with "bad" people who are not "bad". When people are not simplified to good or bad, when there are "redeeming" qualities and juxtaposed with their inhumane vices. If the players want they can choose to have blinders and only to follow anecdotal evidence, but then the GM presents a subtle contrary evidence to mess it all up. (Typically the GM presents a biased view of non-verifiable evidence and testimony, vs the muddy uncertainty of facts in plain sight that follows a chain of evidence against the motivations of the players/ or the conclusions PCs are not suited to deal with)
The GM can prepare from a Web of various spinets, stories of decent into madness and depression of various peoples (there is many to be found online). It would be pretty dark, with no real villain except that the symptom manifest in some disturbing crimes and practices that are accepted in the community and kept hush. Willing Ignorance, Stockholm syndrome, Popular Opinion, and various cognitive landscapes/terrain that hamper most of the advance of the PCs. If the PCs are strangers, give them Isolation, if they are part of the community put them in a warm friendly bubble.
As for take away of the players would be the empathy and the awareness of situation - and a case study method of practicing player skills in Problem Solving (get ready for having no audience lolz).
Another is the GM risk a lot in narrating such a story as their intention can be misinterpreted/misunderstood. The GM will emphasize in the horrific and the disturbing for dramatic effect (duh), and present biased and callous information regarding everyday common place bigotry, abuse, and harassment (I'm a GM who won't risk reputation in running such a game unless its with friends who know me personally and trust me). Which is can be misinterpreted so easily, and triggering many to say the GM is just expressing his "real nature" lolz.
The GM applying a lot of penalties when PCs are in heightened paranoia (and trade off bonuses), checks to sleep, and role-playing many of the costs of being in such a situation (the cost of trust). Since its a game, the GM may grant many cognitive bonuses to morale when the PCs pursue stable and healthy emotions, relationships and attachments. Just realize a GM who basically put weight on the decision of a PCs to be friends with X and showing trust lolz. Definitely there are going to be too few people who would want to play such a game (mostly the morbidly curious). But in such a game, there are times when even bonuses are not enough and the unlikely success happens, everyone rolls to see how things turn out.
1 session is not enough and is just the Pilot episode. Just 2 sessions would be momentum going, and 3rd will be emotionally draining for everyone.
edited for clarity and painful to read grammar :(