hmm... Blackjack. Ugly code in a hurry :p This code does not handle "A" being either 11 or 1. However it shouldn't be hard to add.

play.rb

class Deck
  attr_reader :deck

  def initialize
    @deck = self.class.shuf
  end

  private

  def self.shuf
    deck  = []
    ranks = ["A", "2", "3", "4", "5", "6", "7", "8", "9", "10", "J", "Q", "K"]
    suits = ["♦", "♣", "♥", "♠"]

    ranks.each do |rank|
      suits.each do |suit|
        deck << [rank, suit]
      end
    end
    deck.shuffle
  end
end

def yes_or_no(question)
  puts question
  answer = gets.chomp
  if answer =~ /y|Y/
    return true
  elsif answer =~ /n|N/
    return false
  else
    yes_or_no(question)
  end
end

def value(rank)
  case rank
  when "A"
    return 1
  when "2".."10"
    return rank.to_i
  else
    return 10
  end
end

def total(hand)
  hand.inject(0){ |sum, card| sum + value(card[0]) }
end

def print_cards(hand)
  hand.each { |card| print "#{card[0]}#{card[1]}  " }
end

puts "Welcome to the Blackjack Casino!"
deck = Deck.new.deck
hand = []
dealers_hand = []

while (yes_or_no "\nHit?")
  hand << deck.pop

  print "You now have "
  print_cards(hand)

  if total(hand) > 21
    puts "\nBusted~~"
    sleep 1
    puts "You lost. Good luck next time."
    abort
  end
end

loop do
  dealers_hand << deck.pop
  sleep 1
  print_cards(dealers_hand)

  case
  when total(dealers_hand) > 21
    puts "\nOops~ I busted~~"
    sleep 1
    puts "\nYou win. Congratulations!"
    abort
  when total(dealers_hand) > 16
    sleep 1
    puts "\nOK, let's see who gets this round"
    break
  else
    puts "\nHit me!"
  end
end

sleep 1
puts "You get a #{total(hand)}."
sleep 1
puts "The dealer gets a #{total(dealers_hand)}."
sleep 1
if total(hand) > total(dealers_hand)
  puts "You win. Congratulations!"
elsif total(hand) < total(dealers_hand)
  puts "You lost. Good luck next time."
else
  puts "It's a draw. Let's go grab a beer."
end