I created Pollutocracy, a toy simulation of machines that make energy bolts. They emit smog amidst some other natural and peculiar things. It's randomly generated. It's not interactive.
There's a screenshot to the leftabove. You can compile and run it yourself; instructions are in the README.
I wrote this toy simulation in Haskell and OpenGL 1.x in 2005 and it has aged remarkably well. It survived a Darcs → Git conversion. It's needed only modest updates (caught by the type system) to keep up with Haskell library progress. Of course, OpenGL 1.x style drawing is horribly inefficient, so I'd rewrite it if I wanted to expand this. I might write the simulation code using lens libraries today. I'd find some way to run it in a web browser that's better than screen-capturing video by hand. But it still works!