import socket
 import threading
 from parser import ArgError, Parser
-from game_common import World, Commander
+from game_common import World, CommonCommandsMixin
 
 
-class Game(Commander):
+class Game(CommonCommandsMixin):
     world = World()
     log_text = ''
 
 
         self.position = [0,0]
 
 
-class Commander:
+class CommonCommandsMixin:
 
     def cmd_MAP_SIZE(self, yx):
         """Set self.map_size to yx, redraw self.terrain_map as '?' cells."""
 
         return fib(n-1) + fib(n-2)
 
 
-class Game(game_common.Commander):
+class Game(game_common.CommonCommandsMixin):
 
     def __init__(self, game_file_name):
         import server_.io