It's a pity. Despite all its flaws, the game truly had potential. Had he been able to carry on and polish some things, it could have been something really good. For all the criticism —some of it I levelled myself, always well intentend, since I was really interested in the game—, I think he is leaving with an idea of almost complete failure which is just too hard both on the game and himself. He left the door ajar, and I hope things improve for him and is able to come back in better personal circumstances to pick up where he left it. He might find some still regard his work fondly.
Anyway, at this point, all that matters is the person. I did not pay for this game, so I am not qualified to tell anybody how they should proceed, but I think I would try to be as understanding as I could given the circumstances. As for the rest, I really wish this guy all the best. Depression can be a real bitch, so I hope he can get out of that, improve his life and, hopefully, who knows, give this business another try in the future.