command line tic tac toe

tictactoe.rb

###### some methods #######

def print_board
  puts
  for i in 0..8
    if @the_board[i].nil?
      print "#{i+1}"
    else
      print "#{@the_board[i]}"
    end
    if (i + 1) % 3 == 0 # if it's the end of a row
      print "\n"
    else
      print " "
    end
  end
  puts
end

def change_turns
  if @current_player == "X"
    @current_player = "O"
  else
    @current_player = "X"
  end
end

def update_game_over
  # first let's check if someone has won
  [[0, 3, 6], [1, 4, 7], [2, 5, 8], [0, 1, 2], [3, 4, 5], [6, 7, 8], [0, 4, 8], [2, 4, 6]].each do |winner| # these are all 8 winners
    if @the_board[winner[0]].nil? == false and @the_board[winner[0]] == @the_board[winner[1]] and @the_board[winner[0]] == @the_board[winner[2]]
      return "Player #{@current_player} wins!"
    end
  end

  # if no one has yet won, let's check if the board is full
  if @the_board.include?(nil) == false
    return "Welp, another tie game."
  end

  # this game ain't over til it's over
  return false
end

######## let's get started ########

@the_board = [
  nil, nil, nil,
  nil, nil, nil,
  nil, nil, nil
]

puts "Welcome to tic tac toe by Max Jacobson"
puts
puts "One or two player mode? (1/2)"
print "> "
mode = gets.chomp.to_i

if mode == 1
  puts "Prepare to test your wits against a SUPER smart AI"
  # joking. a good AI would make every game a tie, no?
  # lets let the computer go first half the time
  if rand(0..1) == 0
    @current_player = "X"
  else
    @current_player = "O"
    puts "Let's let the computer go first..."
  end
  sleep 1
else
  @current_player = "X"
end

game_over = false
while game_over == false
  if @current_player == "O" and mode == 1 # if it's time for the computer to move
    # we'll find a random spot on the board that isn't already taken
    thinking = true
    while thinking == true
      new_move = rand(0..8)
      if @the_board[new_move].nil?
        thinking = false
      end
    end
  else # if it's time for a human to move
    # display the board and get their move
    print_board
    puts "#{@current_player}'s move (1-9)"
    print "> "
    new_move = gets.chomp.to_i - 1
  end

  if @the_board[new_move].nil? # if that spot isn't already taken
    @the_board[new_move] = @current_player # update the board
    game_over = update_game_over # check if the game is over
    if game_over == false
      change_turns
    end
  else # if that spot WAS already taken (good try!)
    puts "Sorry, that spot is already taken, try again?"
    sleep 1
  end

end # game over

# once the game is over, display the board one more time and then the results
print_board
puts "#{game_over}"