trjhtr

I have the following program for a multiple choice quiz game. Before I get stuck in some habits, can anyone please review and propose suggestions for improvements?

import random
import time

YES = ['y', 'Y', 'yes', 'Yes', 'YES']
NO = ['n', 'N', 'no', 'No', 'NO']
CLEAR = ['c', 'C', 'clear', 'Clear', 'CLEAR']
QUIT = ['q', 'Q', 'quit', 'Quit', 'QUIT']
MULTIPLECHOICE = ['a', 'b', 'c', 'd']


class QuizGame:
 ''' repository of methods to do with QuizGame
 - get_username
 - play_loop
 - ask_play_again
 - escape_quiz
 - play_quiz
 - read_highscores
 - write_highscores
 - clear_highscores
 - display_highscores
 '''
 questions = 
 1: ('What was the first video game ever made?',
 'a) God of War 9nb) Pacman nc) Pong nd) Tennis for Two',
 'd'),

 2: ('What was the most expensive video game to ever be developed?',
 'a) Destinynb) Call of Duty: Modern Warfare 2 n'
 'c) Grand Theft Auto: V nd) Disney Infinity',
 'b'),

 3: ('What amount of time a day does the average gamer (In the US, '
 'age 13 or older) spend gaming?',
 'a) 54 minutesnb) 25 hoursnc) 2 hoursnd) 30 minutes',
 'a'),

 4: ('Who is the founder of Nintendo?',
 'a) Fusajiro Yamauchinb) Bob Dylannc) Steve Bovairdn'
 'd) Nihonjin no Shimei',
 'a'),

 5: ('What was the most purchased game of 2017?',
 'a) Jesus simnb) Farming Simulator 2017n'
 'c) Call of Duty: WWIInd) Destiny 2',
 'c'),

 6: ('When was E3 [Electronic Entertainment Expo] 2017?',
 'a) 13 Jun 2017 - 15 Jun 2017nb) 13 Jun 2017 - 14 Jun 2017n'
 'c) 15 July 2017 - 13 July 2017nd) 10 Jun 2017 - 18 Jun 2017',
 'a'),

 7: ('What was the most popular console of 2010?',
 'a) Xbox 360nb) PlayStation 3nc) Xbox 1nd) PlayStation 4',
 'a'),

 8: ('Who was the most subscribed gaming youtuber of 2012?',
 'a) PrettyL8rnb) Pewdiepienc) Gregnd) NotGreg',
 'b'),

 9: ('Who won the Game of The Year award 2016?',
 'a) Overwatchnb) Treyarchnc) Blizzardn'
 'd) Rainbow Six Siege',
 'c'),

 10: ('When did DOOM release?',
 'a) December 10, 1993nb) February 23, 1995n'
 'c) January 32, 20019nd) Yesterday',
 'a'), 

 welcometext =
 'nHello , welcome to The Videogame Quiz'
 'nIn this quiz, you will be asked 10 questions about videogames.'
 'nTry your best to answer all 10 correctly. Enter a, b, c or d '
 'ndepending on which answer you think is rightn'

 users = 
 score = 0
 highscore_file = 'highscore.log'

 @classmethod
 def get_username(cls):
 ''' method to ask user for user_name, if user name is Quit then leave.
 Dictionary of cls.users is checked on existing users. If user
 does not exist he/ she is added.
 '''
 user_name = ''
 quit = False
 while len(user_name) < 4 and not quit:
 user_name = input('Hello! What is your name [enter Q(uit) '
 'to leave]?: ').strip().capitalize()
 if user_name in QUIT:
 quit = True

 if not quit:
 if user_name not in cls.users:
 cls.users.update(user_name: 0)
 cls.highscore = 0

 print(cls.welcometext.format(user_name))

 return user_name, quit

 @classmethod
 def play_loop(cls, user_name):
 ''' method to control loop of the quiz, update highscore, and ask
 to play again or not
 '''
 playagain = True
 while playagain:
 print(f'nuser_name, your current highscore is '
 f'cls.users[user_name].n')

 if cls.escape_quiz():
 break

 score = cls.play_quiz()

 if score > cls.users[user_name]:
 cls.users.update(user_name: score)

 playagain = cls.play_again()

 @staticmethod
 def play_again():
 ''' ask player if he/ she wants to play quiz again
 '''
 answered = False
 while not answered:
 answer = input('Do you want to take the quiz again? Y or N: ')
 answered = True

 if answer in YES:
 playagain = True

 elif answer in NO:
 playagain = False

 else:
 answered = False

 return playagain

 @staticmethod
 def escape_quiz():
 ''' ask player twice if he/ she is ready to continue
 '''
 answered = 0
 question = 'nAre you ready to continue? Y or N? '
 while answered < 2:
 answer = input(question)
 print('---------------------------------------')
 answered += 1

 if answer in YES:
 escape_the_quiz = False
 break

 elif answer in NO:
 escape_the_quiz = True
 for i in range(3):
 print('Oh... ok')
 time.sleep(0.5)
 question = 'nNow are you ready to continue? Y or N '

 else:
 print('Yes or no only please!')

 return escape_the_quiz

 @classmethod
 def play_quiz(cls):
 ''' core of quiz asking multiple choice questions. Player can leave
 by entering quit
 '''
 questions = cls.questions.copy()
 question_choice = i for i in range(1, len(questions)+1)
 score = 0
 question_nr = 1

 while questions:
 question = random.sample(question_choice, 1)[0]
 answered = False

 print(f'Question: question_nr of len(cls.questions)')
 print(questions[question][0])
 print(questions[question][1])
 question_nr += 1

 answered = False
 while not answered:
 answer = input('What is your answer?: ').lower()

 if answer in (MULTIPLECHOICE + QUIT):
 answered = True

 else:
 print('ERROR, please input a, b, c or d only please!')

 if answer in QUIT:
 break

 elif answer == questions[question][2]:
 print('Good job! You are correct.n')
 score += 1

 else:
 print('Unfortunately that is not correct! '
 'Better luck next time.n')

 questions.pop(question)
 question_choice.remove(question)

 print(f'Your score is >>> scoren')

 return score

 @classmethod
 def read_highscores(cls):
 ''' read highscores from cls.highscore_file
 '''
 try:
 with open(cls.highscore_file, 'r') as highscores:
 for line in highscores:
 user_name, score = line.split(':')
 cls.users[user_name.strip()] = int(score)

 except Exception as e:
 print('Error in log file, must be format <name: score>')

 @classmethod
 def write_highscores(cls):
 ''' write highscores to cls.highscore_file
 '''
 try:
 with open(cls.highscore_file, 'w') as highscores:
 for name in cls.users:
 highscores.write(': n'.
 format(name, str(cls.users[name])))

 except Exception as e:
 print('Error in log file, must be format <name: score>')

 @classmethod
 def clear_highscores(cls):
 ''' clears the highscore file if confirmed by typing 'CLEAR'
 '''
 answer = input('nDo you want to clear the scores log, '
 'type 'CLEAR' ')

 if answer == 'CLEAR':
 with open(cls.highscore_file, 'w') as highscores:
 highscores.write('')

 @classmethod
 def display_highscores(cls):
 ''' displays highscores in order from high to low
 '''
 print('nHighscores')
 print('-'*40)
 print(':20'.format('Name', 'Score'))
 print('-'*40)

 sorted_output = sorted(QuizGame.users.items(), key=lambda v: v[1],
 reverse=True)
 for line in sorted_output:
 print(f'line[0]:20line[1]')


def main():
 ''' starts the program
 '''
 QuizGame.read_highscores()
 QuizGame.display_highscores()
 quit = False

 while not quit:
 user_name, quit = QuizGame.get_username()
 if not quit:
 QuizGame.play_loop(user_name)

 QuizGame.display_highscores()
 QuizGame.write_highscores()
 QuizGame.clear_highscores()


if __name__ == '__main__':
 main()