Game design in general takes a lot from psychological concepts, and even some neuroscience in the way we design for accessibility. We don't specifically deep dive into it - but build our software based on feedback from our patients through workshops and our game design knowledge.

I don't think I've been stuck on a game design problem - it usually leads to trying different approaches that are more creative, or work arounds. If there is a will there is a way - it is just a question of how much smoke and mirrors you want to use. :)

I think that the most important aspect of any product or game design is where possible reducing user friction. Make it as easy and intuitive to pick up as if it was walking. Drop in and play/use. (That does not mean it cannot be challenging! Dark Souls is amazing, minus accessibility!).