Uninitialized constant Game::World when I try and initialize the World class in Ruby -

so i'm trying create basic text adventure in ruby, , i'm following tutorial (https://jsrn.gitbooks.io/make-your-first-text-adventure-in-ruby/content/creating_the_framework.html)

but when try , run code error:

gamebase.rb:10:in `initialize': uninitialized constant game::world (nameerror)     gamebase.rb:55:in `new'     gamebase.rb:55:in `<main>' 

this code:

from gamebase.rb

dir["gamedir/**.*"].each { |file| require_relative file }  class game   actions = [ :forward, :backward, :look, :attack, :loot, :inventory, :use, :cast   ]    def initialize @world = world.new @player = player.new  start_game   end    private   def start_game while @player.alive?   @current_room = @world.get_room_of(@player)    print_player_status    action = take_player_input   next unless actions.include? action    take_action(action) end   end    def take_player_input print "what do?" gets.chomp.to_sym   end    def take_action(action) case action   when :forward     @world   when :backward     @world   when :look     @world   when :attack     @current_room.interact(@player)   when :loot     @current_room.interact(@player)   when :inventory   when :use   when :cast   end end   end    game.new 

and world.rb

class world    def initialize     @past_rooms = 0     @current_room = 0   end    def move_entity_forward(entity)     @current_room += 1   end    def move_entity_backward(entity)     @current_room -= 1   end    def get_room_of(entity)     if @current_room <= @past_rooms @current_room     else       room.new       @past_rooms += 1 end   end end    class room   attr_accessor :size, :content    def initialize     @content    = get_content     @size       = get_size     @adjetive   = get_adjetive   end    def interact(player)     if @content       @content.interact(player)       @content = nil     else       puts "there isn't here..."     end   end    private   def get_content     [monster, item.sample.new]   end    def get_size     dimensions = [5, 10, 15, 20, 25, 30, 40, 50, 75, 100, 200]     "#{dimensions.sample}'x#{dimensions.sample}'"   end    def get_adjetive     ["well-lit", "dim", "filthy", "suprisingly clean", "round", "muddy", "oppressive"]   end   end 

try adding line top of gamebase.rb:

require_relative 'world' 

this tells ruby interpreter file named world.rb in same folder gamebase.rb , run code in file, define world class. world class available when try use it.