title: Limit client to visit a website with 1 tab and 1 browser?
body: <p>I would like to do something like play.clubpenguin.com. </p>
  
  <p>What it does is that, when you visit the site, maybe using firefox or IE, if you opened a new tab or use other browser, when you visit that site again, it will show something like: "Please close the other browser that opened this page" or something like that. </p>
  
  <p>How to do this? (Its client's request)</p>
  
  <p>More information: The site is Flash site</p>
  
  <p>EDIT: </p>
  
  <p>Ok, i think this is a tough question, well, in general, Can this be done using php, mysql and JS?</p>