There are two different background effects (ColorArt and SpriteArt). Every time you click green flag, one of them will be chosen at random. If you get the sprite animation in background, you can press space key to change sprites. Oh, and today is Diwali - Festival of Lights. Wish you all a very Happy Diwali!!
To remix, use the eraser tool in paint editor to 'draw' your own masks (shapes/text/anything else), and have different animations working in the background to get this effect. You can also make your WordArt interactive by changing the effects based on loudness/video sensing etc.
