如何将类名作为变量传递给ruby中的另一个类

我正在努力学习在 ruby中创建一个多类程序.我编写了一个Engine类和一些其他类,如city,street等,并且在将类名作为变量传递给其他类时遇到了问题.下面的代码抛出错误：“City.rb：15：in’intro’：未定义的局部变量或方法游戏’for#(NameError)”.我在某种程度上理解这个问题,但我不认为这个城市需要知道任何事情
游戏对象,我认为它只需要得到它并传回去.但显然我对如何在类之间传递变量(尤其是类名)有误解.我的设计出了什么问题？

#Game.rb
require './City.rb'
class Engine
  def initialize(city_name,street_name,budget)
    @city = City.new(city_name)
    @city.read_name()
    play(@city,:intro,self)
  end

  def play(place,next_step,engine)
    while true
      next_step = place.method(next_step).call(place,engine)
    end
  end
end

game = Engine.new("Casablanca","Costanza Boulvard",200)

#City.rb
class City
  def initialize(city_name)
    @city_name = city_name
  end

  def read_name()
    puts <<-READ_NAME
    You are in a city called "#{@city_name}".
    READ_NAME
  end

  def intro(place,engine)
    puts "...."
    game.play(@street,:enter,engine)
  end
end

def use_class(myclass)
  x = myclass.new "test"
  x.read_name
end

use_class(City)
# returned -> '    You are in a city called "test".'

@city = City.new(city_name,self)

def initialize(city_name,game)
    @city_name = city_name
    @game = game
  end

@game.play(@street,@game)