Play It Now, Hate Me Later
This is quite possibly the most addictive Internet Waste of Time I've run across yet. It's a game; it's art; it's a puzzle; it's a pet.
Basically, there are four streams of sand-like particles flowing down the screen: sand, water, salt and oil. You can draw wall and floors to contain, mix and redirect them. You can draw in other things like plants, wax or fire to make things happen. There's the ???, which is... well... a fractal virus explosion.
And then there's the little namekuji, a slug-like creature moving around the screen drinking water to grow, avoiding killing salt, and sometimes eating everything. It's kinda cute until you realise fire makes it burn and too much salt makes it explode!
You can adjust the flow, the size of the walls, and the speed of the game. It will fascinate you.
Before you start, make sure to clear a couple of hours out of your schedule.