Something I came across by chance, this is weirdly addicitive:
http://chir.ag/stuff/sand/
"The game involves four different particles falling from the top of the screen, which all look and move similar to sand. The particles resemble sand, water, salt, and oil in color. Along with these four, additional elements can be placed on the screen with the mouse, some that are solid and stationary instead of flowing. By mixing the different elements together, many colorful designs, complex structures, and systems can be created."
I mainly find myself growing plants to hold sand, splash it all with oil and watch it burn. Good times.
TRY IT YESELF.