My brother shown this to me a few days ago. It's not ground breaking or anything but I wasted an hour or two on it. The site itself is Japanese however the instructions are in English (with a little Engrish on the side). It's safe for work and is a decent way to pass the time trying out the various effects.

On a side note I don't know if this is old news or anything. I was never really up to date on popular web games.


http://dan-ball.jp/en/javagame/dust/