Reminds me of something I remember playing with years ago, where you could draw various materials on the screen. Brick, sand, water, and then add different types of explosives. A really fun simulation all in the browser.
Here's another powder simulation, https://powdertoy.co.uk/. This one still has an active community and development team, and people have built all kinds of cool things with it like actual computers that can be programmed with assembly.
The aforementioned sandspiel is excellent, along with orb.farm (by the same author), and (shameless plug) my own entry in the genre: https://github.com/JMS55/sandbox
Anyone remember what this is?