Junglautomata is a simulation toy where you can draw nice landscapes with rock, sand, and water, grow some plants here and there, and then burn it all down. Or alternatively, turn your phone upside down and watch everything start falling in a different direction, or cut a hole in the ground and admire your new infinite waterfall.
Seriously, it's kind of mesmerizing. I personally like starting fires and seeing how long I can keep them burning.
From a technical perspective it's a bit different from other falling sand games, because instead of processing each particle one at a time, it uses cellular automation techniques to process every pixel of the simulation simultaneously on the GPU. This means it's relatively efficient! Also, the water physics is a bit more interesting than in other simulations.
Draw sand, water, fire, rock, steam, plants, and air.
Plants turn to steam when they burn, which turns back to water, which can help grow more plants. Potentially infinite cycle!
Accelerometer-based gravity manipulation. There's also a button, if you don't want to tilt your phone.
You can also play around with Junglautomata online on your computer at http://nebhack.ca/games/junglautomata/play/