After completing a mission or beating a game, an achievement or trophy will pop up. How do I describe such a person who sticks with it, to unlocking all the achievements of a game, no matter what time or effort is required?
I've considered achievements maniac or achievements addictor?
EDIT: I mean to describe someone's personality. That kind of person maybe take too much time on beating challenges in game but never get bored - sort of perfectism and obsession. The word or phrase needs to be considered derogatory.