Mine

piuke@ubuntu:~/Desktop/Piuke/SaturdayNightNinja $ python main.py
Traceback (most recent call last):
  File "main.py", line 148, in ?
    solidPython.main()
  File "main.py", line 48, in main
    self.eventHandler(event)
  File "main.py", line 142, in eventHandler
    self.menus["main"].eventHandler(event)
  File "/home/piuke/Desktop/Piuke/SaturdayNightNinja/gui.py", line 112, in eventHandler
    retval = self.clicked(event.pos)
  File "/home/piuke/Desktop/Piuke/SaturdayNightNinja/gui.py", line 932, in clicked
    entry.callback()
  File "main.py", line 71, in tutorial
    engine = Engine(0)
  File "/home/piuke/Desktop/Piuke/SaturdayNightNinja/engine.py", line 357, in __init__
    self._initSprites()
  File "/home/piuke/Desktop/Piuke/SaturdayNightNinja/engine.py", line 307, in _initSprites
    self.sprites.append(AvatarView(x))
  File "/home/piuke/Desktop/Piuke/SaturdayNightNinja/engine.py", line 59, in __init__
    'steps.wav'))
pygame.error: mixer system not initialized