I would like to have my website display different content while remaining on the same index.php page. The functionality I am after is demonstrated by www.sryth.com. If you sign up for an account, login, and start a new game, you will see what I mean. The address stays the same throughout the game(i.e. www.sryth.com/game/index.php), even as new content is being displayed. How do I achieve this effect??