Some years back, I enjoyed playing around with a 3D program called "KPT Bryce". It was basically a landscape generator, but if you were persistent enough, you could do some cool things with the available tools. I built this scene for fun -- obviously, the big robot/vehicle thing was inspired by the AT-AT walkers in the "Star Wars" movies.
Bryce was one of those "magic" programs which really kept me interested in computers. I remember just watching the rendering process with rapt fascination. -- PL