The trouble is it's another damned if you do and damned if you don't situation.
If you include a minor character with such a condition it could be seen as tokenism.
If you have something like a bipolar character that has powers when manic and is vulnerable when in depression or a Rain Man esque character that remembers everything you'd be criticised for portraying mental illness as superpower as most people with the conditions suffer from them without such benefits.
If you have a supporting OCD character that has to kill a certain amount of faceless enemies for comic relief you'd be insensitive.
If there's a twist where it turns out your character was suffering a hallucination and accidentally killed innocents it would be sensationalism.
Having a main character that hears voices in relatively harmless way may largely be perceived as positive portrayal (and it could be an interesting game mechanic) but even that could be criticised for undermining how serious an issue it can be.
(Who knows what people would make of a zombie game where the main character suffers from Cotard delusion?)
So you have to write in a way that isn't insensitive and doesn't sensationalise or glamorise such conditions while still showing the difficulties such a character would face and fit all that into seamlessly into your game without appearing too preachy or like you're ticking items of a check-list .
There already many cases were games with good intentions on diversity issues (for want of a better term) receive heavy criticism so it's easy to see why writers may think it's better to avoid the issue.
If you include a minor character with such a condition it could be seen as tokenism.
If you have something like a bipolar character that has powers when manic and is vulnerable when in depression or a Rain Man esque character that remembers everything you'd be criticised for portraying mental illness as superpower as most people with the conditions suffer from them without such benefits.
If you have a supporting OCD character that has to kill a certain amount of faceless enemies for comic relief you'd be insensitive.
If there's a twist where it turns out your character was suffering a hallucination and accidentally killed innocents it would be sensationalism.
Having a main character that hears voices in relatively harmless way may largely be perceived as positive portrayal (and it could be an interesting game mechanic) but even that could be criticised for undermining how serious an issue it can be.
(Who knows what people would make of a zombie game where the main character suffers from Cotard delusion?)
So you have to write in a way that isn't insensitive and doesn't sensationalise or glamorise such conditions while still showing the difficulties such a character would face and fit all that into seamlessly into your game without appearing too preachy or like you're ticking items of a check-list .
There already many cases were games with good intentions on diversity issues (for want of a better term) receive heavy criticism so it's easy to see why writers may think it's better to avoid the issue.