`switch(true)` abuse. This is a neat trick, but should obviously never actually be done. See http://stackoverflow.com/q/25373912/617937

gistfile1.php

switch (true)
{
	case (!isset($_GET['action']):
		require('menu.html');
		break;
	case ($_GET['action'] == 'debug'):
		require('core/actions/debug.php');
		break;
	case ($_GET['action'] == 'submit'):
		require('core/actions/submit.php');
		break;
	case ($_GET['action'] == 'admin'):
		header("Location: /login");
		break;
}