Falling Sand Game is the name of a series of Java applets created by Dofi Blog, and noted on the Fark forums. The original version, named World of Sand was later enlarged and rehosted by Chirag Mehta. The game has been popular on community link sites like Digg. Since then, a fan forum has been made, which involves discussion on fan made versions based on World of Sand, and later iterations of the original game such as Pyro sand 1 and 2 and New sand. The games are still quite fun, but they do not have the original touch of world of sand.
EDIT: Oh wow...I feel like a ****. When I tried this last time, I couldn't figure out what I was suppose to do w/ the line. I kept trying to combine the particles and watched as they did nothing. Then I went back the other day and it wouldn't load. Today I scrolled down, saw the game AND THE manipulators @ the bottom. Look! I made a plant! Crap...I was better off when I thought it was broke.