Yep, definitely be smarter to start smaller. PTSD would be a safe thing to focus on to start, and I agree with you that it'd be the most familiar to the widest array of users. And yes, as I mentioned in another comment, I'd be very, very careful, and would seek the input of people with the mental differences in question. I don't want to be me telling what it's like for everyone with, say, OCD. I want instead for these people to tell me directly. I'd seen that video before, and yes, definitely a good one, thanks for reminding me of it. If you're interested, here's another one, with a different style, this video being the catalyst that made me think about this worldbuilding idea, as I liked how the experience was portrayed, and it seemed something that'd be easy to implement in a game: