def cmd_LOGIN(game, nick, connection_id):
     for t in [t for t in game.things if t.type_ == 'player' and t.nickname == nick]:
         raise GameError('name already in use')
-    t = game.thing_types['player'](game)
+    if connection_id in game.sessions:
+        t_id = game.sessions[connection_id]
+        t = game.get_thing(t_id, False)
+        game.io.send('META ' + quote('you rename yourself to: ' + nick), connection_id)
+    else:
+        t = game.thing_types['player'](game)
+        game.things += [t]  # TODO refactor into Thing.__init__?
+        game.sessions[connection_id] = t.id_
+        game.io.send('META ' + quote('you are now: ' + nick), connection_id)
     t.nickname = nick
-    game.things += [t]  # TODO refactor into Thing.__init__?
-    game.sessions[connection_id] = t.id_ 
-    game.io.send('META ' + quote('you are now: ' + nick), connection_id)
     game.io.send('PLAYER_ID %s' % t.id_, connection_id)
 cmd_LOGIN.argtypes = 'string'