RPS.py

#!/usr/bin/python
import random
import sys

def game():
    options = ["rock","paper","scissors"]
    computer_choice = random.choice(options)
    player_choice = (raw_input('\nPlease enter your choice '
                               'of rock, paper, '
                               'or scissors to play:\n>> ')).lower()

    if player_choice ==  computer_choice:
        print ("\nIt is a tie!!")

    elif player_choice == "rock" and computer_choice == "paper":
        print ("\npaper beats rock -- You lost!!")
    elif player_choice == "paper" and computer_choice == "scissors":
        print ("\nscissors beats paper -- You lost!!")
    elif player_choice == "scissors" and computer_choice == "rock":
        print ("\nrock beats scissors -- You lost!!")

    elif player_choice == "rock" and computer_choice == "scissors":
        print ("\nrock beats scissors -- You win!!")
    elif player_choice == "paper" and computer_choice == "rock":
        print ("\npaper beats rock -- You win!!")
    elif player_choice == "scissors" and computer_choice == "paper":
        print ("\nscissors beats paper -- You win!!")

    else:
        print('\nThats not a valid option.')
        game()

    def again():
        choice = raw_input("\nWould you like another game?\n>> ").lower()
        if choice in ["yes", 'y']:
            game()
        elif choice in ["no", 'n']:
            sys.exit()
        else:
            again()

    again()

game()