No, but you can use the Browser plug to check a variable in the url:
Return a query string parameter by name. For example, if the URL ends with index.html?foo=bar&baz=ban, QueryParam("foo") returns bar and QueryParam("baz") returns ban.
I tried this recently, and I think something's changed with the browser object; originally it would would return the address show in the browser (or the top page), so if your game was in a iframe on a homepage it would return "example.com" when you queried the URL, however now it will return "example.com/c3directory/index.html" - the actual path of the file, regardless of the browsers current location.
Other than that, what Newt said is correct; you (at least used to be able to) query the page URL and act based on this, so if the current page the user is on is the one you want, play the game, if not, go to a blank layout or something.