What are some free creative games online?

I'm 14 years old and enjoy creative and imaginative games like powder game and falling sand.But out of those two those are the only ones i can think of.What are some FREE online sites that let you create things or control something.Just a game wheir can control mostly what going on to see what happens like experimenting.
I've already played falling sand and powder game and hell of sand and every other sand game linked to that.