Good for you. I didn't want to pick on you or your colleges so much, I just think your local "genius" has weaknesses like everybody, but in reality your company

Good for you. I didn't want to pick on you or your colleges so much, I just think your local "genius" has weaknesses like everybody, but in reality your company is at fault. They should not mystify him, they should have made sure he shares knowledge with others and brings other up to speed. And as he is gone, they should make sure the code is refactored to suit the documentation level and code style the remaining devs are used to.