Paper Scissors Rock

options = ["Rock", "Paper", "Scissors"]

def RockPaperScissors(p1Choice, p2Choice):
    if p1Choice == p2Choice:
        return 0
    if p1Choice == "Rock":
        return 2 if (p2Choice == "Paper") else 1
    if p1Choice == "Scissors":
        return 2 if (p2Choice == "Rock") else 1
    #p1 must be Paper here
    return 2 if (p2Choice == "Scissors") else 1

while True:
    numPlayers = int(input("How many players are there?"))
    if numPlayers >=2:
        playerChoices = [""]*numPlayers
        for player in range(numPlayers):
            while True:
                playerChoices[player] = input("Player " + str(player + 1) + "?")
                if playerChoices[player] not in options:
                    print ("Not a vaild input.")
                else:
                    break
        for player1 in range(1,numPlayers):
            for player2 in range(player1): # so that players don't play twice
                print ("Player", player2+1,"vs. Player",player1+1,":")
                result = (RockPaperScissors(playerChoices[player1], playerChoices[player2]))
                if not result:
                    print ("Tie.")
                    continue
                if result==1:
                    print ("Player",player1+1,"Wins!")
                    continue
                print ("Player",player2+1,"Wins!")
    elif numPlayers == 1:
        print ("How sad! Player 1 wins by default.")
    else:
        print ("Not enough players!")