我认为这是缩进错误的结果.在您发布的代码中，您有

I think this is the result of an indentation error. In your posted code, you have

class Game(object):

    def __init__(self, start):

    [...]

            print "time. You won!"
            exit(0)

    a_game = Game("central_corridor")
    a_game.play()

这样你就定义了 a_game inside Game 类，当 Game 尚未定义时.将其向左移动以将其移动到 Game 范围之外，即

So that you're defining a_game inside the Game class, when Game isn't defined yet. Shift it to the left to move it outside the Game scope, i.e.

a_game = Game("central_corridor")
a_game.play()

(与 class Game(object): 处于同一级别).

(on the same level as class Game(object):).