Thinking about this issue from another direction. You mentioned he had an issue with chronic fatigue. What if that is actually the main factor for him not bein

Thinking about this issue from another direction. You mentioned he had an issue with chronic fatigue. What if that is actually the main factor for him not being able to focus on work. The psychological factor of not being able to deliver on promises especially since you are family could drive him down a spiral even more. Feeling bad for playing games, then playing even more games out of frustration, because it kills thinking time. I met countless people with similar issues over the years and many of them could resolve their problems changing their habits and diet to a healthier one, making sure they get all the necessary vitamins (especially B12,D if they happen to be vegetarian/vegan), and of course doing physical excercise. Just doing low sets of simple Push-ups, Squats, short running, ... 5 days a week can help tremendously in the first few weeks with mental stability. If the fatigue is not his problem, it could be he is just not believing in the success of your mission/product anymore and feels bad about, does not know how to approach you about it. If he is still believing. Try to attack the health issue, motivation first. You should definitly have a serious talk with him what you both can do to improve the situation.