Based on the original "falling sand" game, this little time-waster lets you draw different elements and watch them interact. Set things on fire, grow a garden, create elaborate set-ups. Most elements can be set to either draw or emit by pressing again on the palette.
The interface is minimal to free up canvas space, but elements names are shown on selection and there are basic instructions and element descriptions when you press "?".
This free version offers 19 elements, of which 13 can also emit (aka "spouts") by selecting them twice.