A person who obeys the rules of correct behaviour and considers himself or herself to be morally better than other people. (Cambridge Dictionary)
One who offends or irritates by observance of proprieties (as of speech or manners) in a pointed manner or to an obnoxious degree. (Merriam – Webster)
If you call someone a prig, you disapprove of them because they behave in a very moral way and disapprove of other people’s behaviour as though they are superior. (Collins Dictionary)
A self-righteously moralistic person who behaves as if they are superior to others. (Oxford Dictionaries)
Win Every Game. Prig.