player_00.rb

# -*- coding: utf-8 -*-
class Player
  attr_reader :position

  def initialize(position)
    @position = position
  end

  def move(direction)
    case direction
    when :up
      @position[:y] -= 10
    when :down
      @position[:y] += 10
    when :left
      @position[:x] -= 10
    when :right
      @position[:x] += 10
    end
  end
end

player = Player.new(:x => 100, :y => 100)
player.move(:up)
p player.position # => {:x => 100, :y => 90}