An attempt to apply mathematical logic to Myst IV Revelation's insane memory puzzles. Turns out the permutations are on the order of 10^55, but this script will run the moves that produce the solution.

myst4memories_solution.rb

class Place
  attr_accessor :name
  attr_accessor :phrases
  attr_accessor :left_place
  attr_accessor :right_place
  def initialize(name, initial_phrases)
    @name = name
    @phrases = initial_phrases
    @left_place = nil
    @right_place = nil
  end
  def show
    puts "#{@name}"
    if @left_place.is_a?(Place) && @right_place.is_a?(Place)
      puts "  #{@left_place.name} <-> #{@right_place.name}"
    end
    @phrases.each do |phrase|
      puts "    #{phrase.id} #{phrase.text}"
    end
  end
end

class Phrase
  attr_accessor :id
  attr_accessor :text
  def initialize(id, text)
    @id = id
    @text = text
  end
end

class Test
  attr_accessor :places
  attr_accessor :current_move
  attr_accessor :current_place
  attr_accessor :phrase_stack
  def initialize(places)
    @places = places
    @current_move = 0
    @current_place = nil
    @phrase_stack = []
  end
  def show
    @places.each do |place|
      place.show
    end
    puts "Current move: #{@current_move}"
    if !@current_place.nil?
      puts "Current place: #{@current_place.name}"
    else
      puts "Current place: (none)"
    end
    if !@phrase_stack.nil? && @phrase_stack.length > 0
      puts "Phrase stack: "
      @phrase_stack.each do |phrase|
        puts "  #{phrase.id} #{phrase.text}"
      end
    else
      puts "Phrase stack: (empty)"
    end
  end
  def availableMoves
    if @phrase_stack.length > 0
      return ['left', 'right']
    else
      # if move stack is empty, we can select Places.
      commandList = []
      @places.each do |place|
        commandList << place.name
      end
      return commandList
    end
  end
  def move(command)
    # Check if move is possible.
    if !self.availableMoves.nil? and self.availableMoves.include? command
      # Execute command.
      if command == 'left'
        # Move left.
        @current_place = @current_place.left_place
        # Shift first phrase off the stack and assign it to left_place.
        @places[@places.index(@current_place)].phrases << @phrase_stack.shift
      elsif command == 'right'
        # Move right.
        @current_place = @current_place.right_place
        # Shift first phrase off the stack and assign it to left_place.
        @places[@places.index(@current_place)].phrases << @phrase_stack.shift
      else
        # Select Place.
        placeIndex = @places.index { |place| place.name == command }
        @current_place = @places[placeIndex]
        # Move Phrases to phrase_stack.
        @phrase_stack = @current_place.phrases
        @places[placeIndex].phrases = []
      end
      # Increment move counter.
      @current_move += 1
    else
      puts "Move not possible"
    end
  end
end


phrase1 = Phrase.new(1, "Daddy's really good at chess.")
phrase2 = Phrase.new(2, "You should play him.")
phrase3 = Phrase.new(3, "I'd like to sis, but I don't have a chess set...")
phrase4 = Phrase.new(4, "You could make one, just like you made my spirit guide...")
phrase5 = Phrase.new(5, "I could...but it's really hard to carve figurines that small.")
phrase6 = Phrase.new(6, "They break so easily.")
phrase7 = Phrase.new(7, "Well, maybe mom and dad could give you a set, as a present.")
phrase8 = Phrase.new(8, "I'll tell them to when I link home.")
phrase9 = Phrase.new(9, "Right. And I suppose you'll tell them to make it out of the same rock as this chamber.")
phrase10 = Phrase.new(10, "That way I'll never be able to break it!")

chessboard = Place.new("chessboard", [phrase8, phrase4, phrase3])
statue = Place.new("statue", [phrase1])
picture = Place.new("picture", [phrase7, phrase9])
book = Place.new("book", [phrase2, phrase5, phrase10])
door = Place.new("door", [phrase6])

# Define Place assocations.
chessboard.left_place = statue
chessboard.right_place = door
statue.left_place = picture
statue.right_place = chessboard
picture.left_place = book
picture.right_place = statue
book.left_place = door
book.right_place = picture
door.left_place = chessboard
door.right_place = book


# Start first test to get solution.
test1 = Test.new([chessboard, statue, picture, book, door])
# test1.show

# Move 1: door, left
test1.move('door')
test1.move('left')
# Move 2: book, left, right, right
test1.move('book')
test1.move('left')
test1.move('right')
test1.move('right')
# Move 3: door, left
test1.move('door')
test1.move('left')
# Move 4: book, left
test1.move('book')
test1.move('left')
# Move 5: door, left
test1.move('door')
test1.move('left')
# Move 6: statue, right
test1.move('statue')
test1.move('right')
# Move 7: chessboard, left, right, right, left, right, left, right
test1.move('chessboard')
test1.move('left')
test1.move('right')
test1.move('right')
test1.move('left')
test1.move('right')
test1.move('left')
test1.move('right')
# Move 8: statue, left
test1.move('statue')
test1.move('left')
# Move 9: chessboard, left, right, left
test1.move('chessboard')
test1.move('left')
test1.move('right')
test1.move('left')
# Move 10: chessboard, left
test1.move('chessboard')
test1.move('left')
# Move 11: door, left, right, left
test1.move('door')
test1.move('left')
test1.move('right')
test1.move('left')
# Move 12: chessboard, right, left
test1.move('chessboard')
test1.move('right')
test1.move('left')
# Move 13: door, left, right
test1.move('door')
test1.move('left')
test1.move('right')
# Move 14: door, left
test1.move('door')
test1.move('left')
# Move 15: picture, left, left, right, right
test1.move('picture')
test1.move('left')
test1.move('left')
test1.move('right')
test1.move('right')
# Move 16: book, right, left
test1.move('book')
test1.move('right')
test1.move('left')
# Move 17: book, left
test1.move('book')
test1.move('left')
# Move 18: picture, left, right
test1.move('picture')
test1.move('left')
test1.move('right')

test1.show