Hi, this is a cool little sandbox engine stuff. It feels satisfying for me to watch stuff falling down, especially the sand. Probably out of all the materials the sand has the best visual texture.
The game probably took between 1 and 2 minutes for my first load. The percentage finished at around 18%. On the second load and afterwards, the simulator loads instantly at 1%.
I didn't encounter any bugs or crashes. But I was only running the application for around 5 minutes playing around with it.
Just a little bit regarding the visual... The "tar/pitch" material has a very dark color that seem to blend with the background so it's very hard to see. Perhaps tweaking the visual contrast a bit will make it more readable.