Puzzle Ecstasy

Puzzle ecstasy is a rare condition in which extreme puzzle enthusiasts become so enraptured by the activity of puzzle-making that they are unable to respond or engage with the outside world for significant lengths of time.

This guy I knew who was into puzzles, was a nice guy and all... but eventually, he became so into it that he was inflicted with puzzle ecstasy--always intensely concentrating, always aloof. By the end of it, he wasn't really there at all any more...