<?php

$weapons = ['fists', 'whip', 'gun'];

$indyWeapon = "";

$opponentWeapon = $weapons[rand(0,2)];

switch ($opponentWeapon) {
    case 'fists';
        $indyWeapon = "gun";
        break;
    case 'whip';
        $indyWeapon = "fists";
        break;
    case 'gun';
        $indyWeapon = "whip";
        break;
}

echo $indyWeapon;