Splash page for drupal 7 website
I would recommend to take advantage of jQuery over Flash. As Mohammed suggested, you could try the TinyBox module.

But, the other option is the Splashify module:


  Display a splash page anywhere on your site by redirecting the user,
  showing a lightbox, or displaying a popup. This module is designed to
  be search engine friendly, mobile device friendly and offers multiple
  configuration options.